🐢 Make `!Send` resources `thread_local!`

[joshua-holmes]

This is a sub-issue of #17667. See that issue for more high-level details.

What problem does this solve or what need does it fill?

We are using !Send resources to store mostly global data, such as handles, winit windows, etc. This blocks the resources-as-components effort, which seeks to eliminate the usage of resources.

What solution would you like?

In order to unblock resources-as-components, we need to remove any !Send components and replace them with the use of thread_local!. The benefit of using thread_local! in this context is that the !Send resources we are working with are (at least sometimes) !Sync. Wrapping a var in thread_local! ensures safety without requiring the wrapped type to be Sync or Send.

What alternative(s) have you considered?

We have talked about:

• Using static vars without thread_local!, but that requires the var be Sync.
• Creating !Send Worlds to store this data. This is the long term plan (see parent issue), but right now we just need a short-term solution so resources-as-components is unblocked