Remove is_like_X flags from target specs

[brson]

Today target specs have is_like_openbsd, is_like_osx, is_like_solaris, is_like_windows, is_like_android, is_like_msvc fields. These all seem to amount to querying target_os. They could instead be methods on target spec.

cc #36900 (comment)

[nagisa]

When I was writing the RFC on Target Bundles, it didn’t seem to me that target_os and is_like* are interchangeable. The RFC I linked here also has a proposal on how to adjust target spec to get rid of these is_like fields :)

[jackh726]

Going to go ahead and close this, since this might not even be possible, and is old enough that nobody will probably work on this.

[petrochenkov]

cc #98214