make zig compiler processes live across rebuilds

Changes the `make` function signature to take an options struct, which
additionally includes `watch: bool`. I intentionally am not exposing
this information to configure phase logic.

Also adds global zig cache to the compiler cache prefixes.

Closes #20600

lib/std/Build/Step/UpdateSourceFiles.zig

@@ -67,8 +67,8 @@ pub fn addBytesToSource(usf: *UpdateSourceFiles, bytes: []const u8, sub_path: []
     }) catch @panic("OOM");
 }
 
-fn make(step: *Step, prog_node: std.Progress.Node) !void {
-    _ = prog_node;
+fn make(step: *Step, options: Step.MakeOptions) !void {
+    _ = options;
     const b = step.owner;
     const usf: *UpdateSourceFiles = @fieldParentPtr("step", step);