fix(windows): fix directory cache regression "expected to end with a trailing slash" (#9144)

* okaaaaaaaay

* Revert "resolver: fix debug mode crash in test/bundler/bun-build-api.test.ts (#9140)"

This reverts commit 331d079dad.

* correctly fix the cache bust bug

this was introduced a couple of commits ago in my random fixes,
where i put the wrong fix to another directory caching bug.

i still stand by the assertion in place despite it causing many people
issues. it's precense will prevent subtle module resolutions failures.

* add an extra comment

* fix building a release build locally

* add a better test case for 3216

* staging

* fix mac issues

* ok

---------

Co-authored-by: Jarred Sumner <jarred@jarredsumner.com>

src/string_immutable.zig

@@ -742,6 +742,20 @@ pub fn withoutTrailingSlashWindowsPath(this: string) []const u8 {
     return href;
 }
 
+/// This will remove ONE trailing slash at the end of a string,
+/// but on Windows it will not remove the \ in "C:\"
+pub fn pathWithoutTrailingSlashOne(str: []const u8) []const u8 {
+    return if (str.len > 0 and charIsAnySlash(str[str.len - 1]))
+        if (Environment.isWindows and str.len == 3 and str[1] == ':')
+            // Preserve "C:\"
+            str
+        else
+            // Remove one slash
+            str[0 .. str.len - 1]
+    else
+        str;
+}
+
 pub fn withoutLeadingSlash(this: string) []const u8 {
     return std.mem.trimLeft(u8, this, "/");
 }