fix: which should use cwd if given a relative filepath (#9761)

* Revert "fix!: do not lookup cwd in which (#9691)"

This reverts commit 4869ebff24.

* fix which implementation to be more accurate

* t

* which tests windows

* [autofix.ci] apply automated fixes

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

src/StandaloneModuleGraph.zig

@@ -713,6 +713,7 @@ pub const StandaloneModuleGraph = struct {
                         if (bun.which(
                             &whichbuf,
                             bun.getenvZ("PATH") orelse return error.FileNotFound,
+                            "",
                             bun.argv()[0],
                         )) |path| {
                             return bun.toFD((try std.fs.cwd().openFileZ(path, .{})).handle);