fix: windows functionality and tests

[peakschris]

There are four issues when running on windows:

1. Tests fail on windows due to issues in bazel-starlib #330
2. Tests fail on windows with 'FINDSTR: /= ignored' #331
3. 17 bzlformat_lint_tests fail on windows with 'buildifier command not found' #332
4. remove_child_wksp_symlinks_test fails on windows #333

This PR fixes 3 and 4.

There are related PRs in bazel-skylib and bazel-starlib. There is no dependency -- the PRs can close in any order.

• fix: windows issues cgrindel/bazel-starlib#446 (fixes 1)
• feat: case insensitive diff_test and fix manifest bug bazelbuild/bazel-skylib#527 (fixes 2)

Test results:

Before:
--enable_runfiles: 0 pass
--noenable_runfiles: 0 pass

After this PR:
--enable_runfiles: 52 pass, 19 failures
--noenable_runfiles: 51 pass, 20 failures (17 are doc diff-tests due to bazel-starlib)

After this PR, together with wip PRs for 1 and 2:
--enable_runfiles: 71 pass, 0 failures
--noenable_runfiles: 51 pass, 20 failures (all due to bazel-starlib)

[peakschris]

I've updated this PR, could someone please approve the CI workflow?

[cgrindel]

I approved the CI.