Document how to use MCP support in LLDB. I expect this to change
significantly as the feature matures. For now it covers configuring the
server and two example clients.

The only difference from the original PR are the added BRIEF and
FULL_DOCS arguments to define_property, which are required for
cmake<3.23.

Causes failures on several bots.

This reverts commits 714b2fdf3a385e5b9a95c435f56b1696ec3ec9e8 and
e7c1da7c8ef31c258619c1668062985e7ae83b70.

Some inter-plugin dependencies are okay, others are not. Yet others not,
but we're sort of stuck with them. The idea is to be able to prevent
backsliding while making sure that acceptable dependencies are..
accepted. For context, see
https://github.com/llvm/llvm-project/pull/139170 and the attached
changes to the documentation.

This was removed in https://github.com/llvm/llvm-project/pull/135343 in
favour of making it a format variable, which we do here. This follows
the precedent of the `[opt]` and `[artificial]` markers.

Before:
```
 thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 1.2
 * frame #0: 0x000000010000037c a.out`inlined1() at inline.cpp:4:3
   frame #1: 0x000000010000037c a.out`regular() at inline.cpp:6:17
   frame #2: 0x00000001000003b8 a.out`inlined2() at inline.cpp:7:43
   frame #3: 0x00000001000003b4 a.out`main at inline.cpp:10:3
   frame #4: 0x0000000186345be4 dyld`start + 7040
```

After (note the `[inlined]` markers):
```
thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 1.2
* frame #0: 0x000000010000037c a.out`inlined1() at inline.cpp:4:3 [inlined]
  frame #1: 0x000000010000037c a.out`regular() at inline.cpp:6:17
  frame #2: 0x00000001000003b8 a.out`inlined2() at inline.cpp:7:43 [inlined]
  frame #3: 0x00000001000003b4 a.out`main at inline.cpp:10:3
  frame #4: 0x0000000186345be4 dyld`start + 7040
```

rdar://152642178

Currently, the type `T`'s summary formatter will be matched for `T`,
`T*`, `T**` and so on. This is unexpected in many data formatters. Such
unhandled cases could cause the data formatter to crash. An example
would be the lldb's built-in data formatter for `std::optional`:
```
$ cat main.cpp
#include <optional>

int main() {
  std::optional<int> o_null;
  auto po_null = &o_null;
  auto ppo_null = &po_null;
  auto pppo_null = &ppo_null;
  return 0;
}
$ clang++ -g main.cpp && lldb -o "b 8" -o "r" -o "v pppo_null"
[lldb crash]
```

This change adds an options `--pointer-match-depth` to `type summary
add` command to allow users to specify how many layer of pointers can be
dereferenced at most when matching a summary formatter of type `T`, as
Jim suggested
[here](https://github.com/llvm/llvm-project/pull/124048/#issuecomment-2611164133).
By default, this option has value 1 which means summary formatter for
`T` could also be used for `T*` but not `T**` nor beyond. This option is
no-op when `--skip-pointers` is set as well.

I didn't add such option for `type synthetic add`, `type format add`,
`type filter add`, because it useful for those command. Instead, they
all have the pointer match depth of 1. When printing a type `T*`, lldb
never print the children of `T` even if there is a synthetic formatter
registered for `T`.

This PR is a subset of the commits made in
https://github.com/swiftlang/llvm-project/pull/10710.

The most notable change is the addition of `PrefixRange` and
`SuffixRange` which are a catch-all to track anything after or before a
function's demangled name. In the case of Swift, this allows to add
support for name highlighting without having to track the range of the
scope and specifiers of a function (this will come in another PR).