The LLVM Coding Standards [1] specify that:
> [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.
Historically, that hasn't been something we've enforced in LLDB, but in
the past year or so I've started to pay more attention to this in code
reviews. This PR brings more error messages in compliance, further
increasing consistency.
I also adopted `createStringErrorV` where it improved the code as a
drive-by for lines I was already touching.
[1] https://llvm.org/docs/CodingStandards.html#error-and-warning-messages
Assisted-by: Claude Code
This makes the constructions of string errors more concise and more
consistent, mainly by removing the `inconvertibleErrorCode()`.
Additional changes replace `createStringError(formatv(...), ...)` with
`createStringErrorV(...)`.
Assisted-by: Claude
