build: support zig build test

[DonIsaac]

Upstack from #15914, which must be merged first.

What does this PR do?

Adds zig build test support in build.zig. I've added a single test to glob/ascii.zig as a POC. I'll add more test suites, plus integrate this into cmake, in an upstack PR.

How did you verify your code works?

Affects testing only, no meaningful source changes.

[robobun]

^{Updated 5:20 PM PT - Dec 20th, 2024}

✅ @DonIsaac, your commit d98c847 has passed in #8361! 🎉

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🧪   try this PR locally:

bunx bun-pr 15915