[workflows] (almost) rewrite update_examples.yml workflow

[JohnnyCena123]

• switch windows to Ubuntu, because rexm would NOT work on windows
• build rexm and run it to update and sync all the examples on push
• build examples for web in order to push them to the raylib.com website repository
• add personal access token (@raysan5 you need to add your own here) to allow the runner to push to the raylib.com repo

p.s. a lot of files changed because the workflow already started working :) hence it has made some updates while I was working on this PR

[JohnnyCena123]

also, please squash merge this PR if at all

[JohnnyCena123]

to anyone wondering about the huge amount of commits, when testing CI stuff basically each push is a try to make it work. so I spent a couple of tries