fix(which/windows): ignore file extension case

[SunsetTechuila]

What does this PR do?

This fixes #10101

• Documentation or TypeScript types (it's okay to leave the rest blank in this case)
• Code changes

How did you verify your code works?

I compiled the executable and tested it manually

[paperclover]

can you add a unit test to verify this works?

[SunsetTechuila]

Ok, I will

[SunsetTechuila]

@paperdave done
but I have no idea how to run this test
don't think this can be done with js/ts test since this is a windows-specific function

[gvilums]

We don't currently run zig tests in our test suite. Instead, I suggest adding something like the following to which.test.ts:

test.if(isWindows)("which is case-insensitive", () => {
  expect(which("cmd.EXE")).toBe("C:\\Windows\\system32\\cmd.exe");
})

(feel free to adjust)

[SunsetTechuila]

oh, so you have os-specific js/ts tests, i see now

[SunsetTechuila]

@gvilums done

[Jarred-Sumner]

Thank you