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>

Details: detailed_command_telemetry (bool) and command_id (int) could
already be freed when the dispatcher's dtor runs. So we should just copy
them into the lambda since they are cheap.