feat: support timeouts and deadlines

[pcolladosoto]

This commit adds support for specifying deadlines for read and write operations over UARTs in one of two ways:

1. By providing a deadline as an absolute time in the future as was done before. These deadlines can be 'refreshed' through the set_deadline methods.

2. By providing a timeout with which a new deadline will be computed upon performing a read or write operation.

This allows for a precise handling of deadlines when leveraging the std.Io.{Reader,Writer} interface semantics.

Closes #1017

[pcolladosoto]

Hi @Grazfather, @mattnite! Feel free to make any comments and/or changes: I'm by no means a Zig expert!

For instance, I believe the explicit dereference in the set_deadline methods might not be needed and I'd be fine with deleting it. Also, the naming can surely be improved (i.e. I'm not completely sold on the TimeFrontier type name) and some documentation can be added; I just deferred that a bit to get a feel for what might be needed to meet your requirements.

Thanks a ton for your time!

[tact1m4n3]

Solid work! I like the direction of this. I only have a few style suggestions.

[tact1m4n3]

Also CI formatting seems to fail. You should run zig fmt on the file. Or you can just setup your editor to do that on save so you don't have to think about it.

[pcolladosoto]

Hi @tact1m4n3! Thanks a ton for the input. I guess everything should be addressed and the pipelines are passing except for a the website generation which apparently fails when not being able to pull an external dependency.

I'd be more than happy to squash all the commits before merging so as not to pollute main too much: up to you :P

Thanks again for the input!