Actually emit a warning, rather than an error, when there's an .lldbinit
file in the current directly. Currently, the message is prepended by
"error" which looks rather odd, as the warning refers to itself as a
warning.

The LLVM Style Guide says the following about error and warning messages
[1]:

> [T]o match error message styles commonly produced by other tools,
> start the first sentence with a lowercase letter, and finish the last
> sentence without a period, if it would end in one otherwise.

I often provide this feedback during code review, but we still have a
bunch of places where we have inconsistent error message, which bothers
me as a user. This PR identifies a handful of those places and updates
the messages to be consistent.

[1] https://llvm.org/docs/CodingStandards.html#error-and-warning-messages

This adjusts the ProtocolServer command to default to create a new
connection listening on `localhost:0` and adds a new `ServerMetadata`
details to `~/.lldb/mcp/lldb-<pid>.json` to record information about the
current MCP server.

This can be consumed by the lldb-mcp binary to establish a connection
from an LLM client.

---------

Co-authored-by: Jonas Devlieghere <jonas@devlieghere.com>

Introduces `_regexp-step`, a step command which additionally allows for
stepping into a target function. This change updates `step` and `s` to
be aliases for `_regexp-step`.

The existing `sif` alias ("Step Into Function") is not well known
amongst users. This change updates `step` and `s` to also work like
`sif`, taking an optional function name.

This is implemented to not break uses of `step` or `s` with a flag, for
example running `step -r func_to_avoid` works as expected.

This is a continuation of 68fd102, which did the same thing but only for
StopInfo. Using make_shared is both safer and more efficient:

- With make_shared, the object and the control block are allocated
  together, which is more efficient.
- With make_shared, the enable_shared_from_this base class is properly
  linked to the control block before the constructor finishes, so
  shared_from_this() will be safe to use (though still not recommended
  during construction).

`(lldb) b` can be used in two different ways:
1. Running `b` without arguments, it lists all existing breakpoints.
2. Running `b` with arguments, it adds breakpoints.

However, the help message doesn't mention the first use case. This patch
adds help message to mention it.

**Without patch**:
```
(lldb) help b
Set a breakpoint using one of several shorthand formats.  Expects 'raw' input (see 'help raw-input'.)

Syntax:
_regexp-break <filename>:<linenum>:<colnum>
              main.c:12:21          // Break at line 12 and column 21 of main.c
...
```

**With patch**:
```
(lldb) help b
Set a breakpoint using one of several shorthand formats, or list the
existing breakpoints if no arguments are provided.  Expects 'raw' input
(see 'help raw-input'.)

Syntax:
_regexp-break <filename>:<linenum>:<colnum>
              main.c:12:21          // Break at line 12 and column 21 of main.c
...
_regexp-break
                                    // List the existing breakpoints
```

This PR adds an MCP (Model Context Protocol ) server to LLDB. For
motivation and background, please refer to the corresponding RFC:
https://discourse.llvm.org/t/rfc-adding-mcp-support-to-lldb/86798

I implemented this as a new kind of plugin. The idea is that we could
support multiple protocol servers (e.g. if we want to support DAP from
within LLDB). This also introduces a corresponding top-level command
(`protocol-server`) with two subcommands to `start` and `stop` the
server.

```
(lldb) protocol-server start MCP tcp://localhost:1234
MCP server started with connection listeners: connection://[::1]:1234, connection://[127.0.0.1]:1234
```

The MCP sever supports one tool (`lldb_command`) which executes a
command, but can easily be extended with more commands.

Use the current frame's language to lookup commands provided by language plugins.

This means commands like `language {objc,cplusplus} <command>` can be used directly, without using the `language <lang>` prefix.

For example, when stopped on a C++ frame, `demangle _Z1fv` will run `language cplusplus demangle _Z1fv`.

rdar://149882520

Fixes https://github.com/llvm/llvm-project/issues/22981

If `settings set use-color` is changed when lldb is running it does not take effect. 
This is fixes that.

---------

Signed-off-by: Ebuka Ezike <yerimyah1@gmail.com>
Co-authored-by: Jonas Devlieghere <jonas@devlieghere.com>