[build.zig] Drop support for 0.11.0 and use more idiomatic build script code (#3927)

* Remove support for 0.11.0, and make build script more idiomatic
+ remove all 0.11.0 compatibility functions
+ remove most LazyPath .path variants
  + I didn't touch emscripten, I don't know if its relative or absolute
+ change all absolute paths to use .cwd_relative
+ only use the builder allocator
+ have local dependencies use the package manager
+ make adding raygui more flexible
+ use zig-cache for generated wayland files

* Remove support for 0.11.0 in examples/build.zig

* update examples further and add clarifying comment on addRaygui

build.zig

@@ -1,7 +1,11 @@
 const std = @import("std");
 const raylib = @import("src/build.zig");
 
-// This has been tested to work with zig 0.11.0 and zig 0.12.0-dev.3632+7fb5a0b18
+// This has been tested to work with zig 0.12.0
 pub fn build(b: *std.Build) !void {
     try raylib.build(b);
 }
+
+// expose helper functions to user's build.zig
+pub const addRaylib = raylib.addRaylib;
+pub const addRaygui = raylib.addRaygui;