Always accept = or space as delimiters when parsing common command line parameters.

[BillyONeal]

Resolves #11456.

[BillyONeal]

CI failed because repo.msys.org is down.

[strega-nil]

Those are a few of the things I've noticed, but the big thing I'd like to see is this working for options to commands. This isn't necessary for this first pass, however. The enum class thing is a necessity before I approve.

[ras0219-msft]

I'd like to see an enum class over size_t as the return of try_parse_argument_as_option(); otherwise LGTM.

[BillyONeal]

@strega-nil Do you have an example command like you want to work for your more complete desired overhaul that doesn't work with the current state of this PR? Out of band you said --x-feature but that option doesn't seem to exist...

[strega-nil]

@BillyONeal --x-feature is an option for the install command, not a global option: https://github.com/microsoft/vcpkg/blob/master/toolsrc/src/vcpkg/install.cpp#L549

[BillyONeal]

@BillyONeal --x-feature is an option for the install command, not a global option: https://github.com/microsoft/vcpkg/blob/master/toolsrc/src/vcpkg/install.cpp#L549

I tried it with the install command and that didn't work. But I didn't try with a manifest so that likely explains it ¯_(ツ)_/¯

[strega-nil]

Ah, yeah, it's a manifest-only option.