[bun:test] Implement test.root configuration option

src/bunfig.zig

@@ -191,6 +191,14 @@ pub const Bunfig = struct {
                 }
             }
 
+            if (comptime cmd == .TestCommand) {
+                if (json.get("test")) |test_| {
+                    if (test_.get("root")) |root| {
+                        this.ctx.debug.test_directory = root.asString(this.allocator) orelse "";
+                    }
+                }
+            }
+
             if (comptime cmd.isNPMRelated() or cmd == .RunCommand or cmd == .AutoCommand) {
                 if (json.get("install")) |_bun| {
                     var install: *Api.BunInstall = this.ctx.install orelse brk: {

src/cli.zig

@@ -838,6 +838,8 @@ pub const Command = struct {
         macros: ?MacroMap = null,
         editor: string = "",
         package_bundle_map: bun.StringArrayHashMapUnmanaged(options.BundlePackage) = bun.StringArrayHashMapUnmanaged(options.BundlePackage){},
+
+        test_directory: []const u8 = "",
     };
 
     pub const Context = struct {