This patch adds the notion of "Facade" locations which can be reported
from a ScriptedResolver instead of the actual underlying breakpoint
location for the breakpoint. Also add a "was_hit" method to the scripted
resolver that allows the breakpoint to say which of these "Facade"
locations was hit, and "get_location_description" to provide a
description for the facade locations.

I apologize in advance for the size of the patch. Almost all of what's
here was necessary to (a) make the feature testable and (b) not break
any of the current behavior.

The motivation for this feature is given in the "Providing Facade
Locations" section that I added to the python-reference.rst so I won't
repeat it here.

rdar://152112327

The addition of the StopCondition in the lldb_private layer meant that
clearing a breakpoint condition with:

sb_break.SetCondition(nullptr);

now crashes. Also, GetCondition for an empty condition used to return a
nullptr, but now it returns "".

This patch fixes that crash and makes the SB GetCondition always return
nullptr for an empty condition.

LLDB breakpoint conditions take an expression that's evaluated using the
language of the code where the breakpoint is located. Users have asked
to have an option to tell it to evaluate the expression in a specific
language.

This is feature is especially helpful for Swift, for example for a
condition based on the value in memory at an offset from a register.
Such a condition is pretty difficult to write in Swift, but easy in C.

This PR adds a new argument (-Y) to specify the language of the
condition expression. We can't reuse the current -L option, since you
might want to break on only Swift symbols, but run a C expression there
as per the example above.

rdar://146119507

This adds SBBreakpoint::SetIsHardware, allowing clients to mark an
existing breakpoint as a hardware breakpoint purely through the API.
This is safe to do after creation, as the hardware/software distinction
doesn't affect how breakpoint locations are selected.

In some cases (e.g. when writing a trap instruction would alter program
behavior), it's important to use hardware breakpoints. Ideally, we’d
extend the various `Create` methods to support this, but given their
number, this patch limits the scope to the post-creation API. As a
workaround, users can also rely on target.require-hardware-breakpoint or
use the `breakpoint set` command.

rdar://153528045

Lots of code around LLDB was directly accessing the target's section
load list. This NFC patch makes the section load list private so the
Target class can access it, but everyone else now uses accessor
functions. This allows us to control the resolving of addresses and will
allow for functionality in LLDB which can lazily resolve addresses in
JIT plug-ins with a future patch.

This patch removes all of the Set.* methods from Status.

This cleanup is part of a series of patches that make it harder use the
anti-pattern of keeping a long-lives Status object around and updating
it while dropping any errors it contains on the floor.

This patch is largely NFC, the more interesting next steps this enables
is to:
1. remove Status.Clear()
2. assert that Status::operator=() never overwrites an error
3. remove Status::operator=()

Note that step (2) will bring 90% of the benefits for users, and step
(3) will dramatically clean up the error handling code in various
places. In the end my goal is to convert all APIs that are of the form

`    ResultTy DoFoo(Status& error)
`
to

`    llvm::Expected<ResultTy> DoFoo()
`
How to read this patch?

The interesting changes are in Status.h and Status.cpp, all other
changes are mostly

` perl -pi -e 's/\.SetErrorString/ = Status::FromErrorString/g' $(git
grep -l SetErrorString lldb/source)
`
plus the occasional manual cleanup.

This PR is in reference to porting LLDB on AIX.

Link to discussions on llvm discourse and github:
1.  https://discourse.llvm.org/t/port-lldb-to-ibm-aix/80640
2.  #101657 

The complete changes for porting are present in this draft PR:
https://github.com/llvm/llvm-project/pull/102601

The changes on this PR are intended to avoid namespace collision for
certain typedefs between lldb and other platforms:
1. tid_t --> lldb::tid_t
2. offset_t --> lldb::offset_t

Cppcheck recommends using a const reference for range variables in a
for-each loop.
This avoids unnecessary copying of elements, improving performance.

Caught by cppcheck -
lldb/source/API/SBBreakpoint.cpp:717:22: performance: Range variable
'name' should be declared as const reference. [iterateByValue]
lldb/source/API/SBTarget.cpp:1150:15: performance: Range variable 'name'
should be declared as const reference. [iterateByValue]
lldb/source/Breakpoint/Breakpoint.cpp:888:26: performance: Range
variable 'name' should be declared as const reference. [iterateByValue]
lldb/source/Breakpoint/BreakpointIDList.cpp:262:26: performance: Range
variable 'name' should be declared as const reference. [iterateByValue]

Fix #91213
Fix #91217
Fix #91219
Fix #91220

StreamFile subclasses Stream (from lldbUtility) and is backed by a File
(from lldbHost). It does not depend on anything from lldbCore or any of its
sibling libraries, so I think it makes sense for this to live in
lldbHost instead.

Differential Revision: https://reviews.llvm.org/D157460