[lldb] Unify CalculateMD5 return types (#91029)
This is a retake of https://github.com/llvm/llvm-project/pull/90921
which got reverted because I forgot to modify the CalculateMD5 unit test
I had added in https://github.com/llvm/llvm-project/pull/88812
The prior failing build is here:
https://lab.llvm.org/buildbot/#/builders/68/builds/73622
To make sure this error doesn't happen, I ran `ninja
ProcessGdbRemoteTests` and then executed the resulting test binary and
observed the `CalculateMD5` test passed.
# Overview
In my previous PR: https://github.com/llvm/llvm-project/pull/88812,
@JDevlieghere suggested to match return types of the various calculate
md5 functions.
This PR achieves that by changing the various calculate md5 functions to
return `llvm::ErrorOr<llvm::MD5::MD5Result>`.
The suggestion was to go for `std::optional<>` but I opted for
`llvm::ErrorOr<>` because local calculate md5 was already possibly
returning `ErrorOr`.
To make sure I didn't break the md5 calculation functionality, I ran
some tests for the gdb remote client, and things seem to work.
# Testing
1. Remote file doesn't exist
1. Remote file differs
1. Remote file matches
## Test gaps
Unfortunately, I had to modify
`lldb/source/Plugins/Platform/MacOSX/PlatformDarwinDevice.cpp` and I
can't test the changes there. Hopefully, the existing test suite / code
review from whomever is reading this will catch any issues.
95f208f97e