This is a follow-on to:

https://github.com/llvm/llvm-project/pull/82085

The completer for register names was missing from the argument table. I
somehow missed that the only register completer test was x86_64, so that
test broke.

I added the completer in to the right slot in the argument table, and
added a small completions test that just uses the alias register names.
If we end up having a platform that doesn't define register names, we'll
have to skip this test there, but it should add a sniff test for
register completion that will run most everywhere.

This reverts commit 21631494b068d9364b8dc8f18e59adee9131a0a5.

Reverted because of greendragon failure:

******************** TEST 'lldb-api :: functionalities/completion/TestCompletion.py' FAILED ********************
Script:

Most commands were adding argument completion handling by themselves,
resulting in a lot of unnecessary boilerplate. In many cases, this could
be done generically given the argument definition and the entries in the
g_argument_table.

I'm going to address this in a couple passes. In this first pass, I
added handling of commands that have only one argument list, with one
argument type, either single or repeated, and changed all the commands
that are of this sort (and don't have other bits of business in their
completers.)

I also added some missing connections between arg types and completions
to the table, and added a RemoteFilename and RemotePath to use in places
where we were using the Remote completers. Those arguments used to say
they were "files" but they were in fact remote files.

I also added a module arg type to use where we were using the module
completer. In that case, we should call the argument module.

[lldb] Part 2 of 2 - Refactor `CommandObject::DoExecute(...)` to return
`void` instead of ~~`bool`~~

Justifications:
- The code doesn't ultimately apply the `true`/`false` return values.
- The methods already pass around a `CommandReturnObject`, typically
with a `result` parameter.
- Each command return object already contains:
	- A more precise status
	- The error code(s) that apply to that status

Part 1 refactors the `CommandObject::Execute(...)` method.
- See
[https://github.com/llvm/llvm-project/pull/69989](https://github.com/llvm/llvm-project/pull/69989)

rdar://117378957

Enable completion of variables for `dwim-print` command.

Differential Revision: https://reviews.llvm.org/D145124

Adopt `expression`'s options in `dwim-print`.

This is primarily added to support the `--language`/`-l` flag.

Differential Revision: https://reviews.llvm.org/D144114

Add support for the `--gdb-format`/`-G` flag to `dwim-print`.

The gdb-format flag allows users to alias `p` to `dwim-print`.

Differential Revision: https://reviews.llvm.org/D141425

Implements `dwim-print`, a printing command that chooses the most direct,
efficient, and resilient means of printing a given expression.

DWIM is an acronym for Do What I Mean. From Wikipedia, DWIM is described as:

  > attempt to anticipate what users intend to do, correcting trivial errors
  > automatically rather than blindly executing users' explicit but
  > potentially incorrect input

The `dwim-print` command serves as a single print command for users who don't
yet know, or prefer not to know, the various lldb commands that can be used to
print, and when to use them.

This initial implementation is the base foundation for `dwim-print`. It accepts
no flags, only an expression. If the expression is the name of a variable in
the frame, then effectively `frame variable` is used to get, and print, its
value. Otherwise, printing falls back to using `expression` evaluation. In this
initial version, frame variable paths will be handled with `expression`.

Following this, there are a number of improvements that can be made. Some
improvements include supporting `frame variable` expressions or registers.

To provide transparency, especially as the `dwim-print` command evolves, a new
setting is also introduced: `dwim-print-verbosity`. This setting instructs
`dwim-print` to optionally print a message showing the effective command being
run. For example `dwim-print var.meth()` can print a message such as: "note:
ran `expression var.meth()`".

See https://discourse.llvm.org/t/dwim-print-command/66078 for the proposal and
discussion.

Differential Revision: https://reviews.llvm.org/D138315