[receiver/github] add support for tracing github actions

[kevinschoonover]

Description

Adds support for tracing github action executions. Github actions only gives up to seconds so things that take < 1 second are reported as 0.

Testing

Added basic scaffolding to unit tests the components, but unfamiliar with the best practices here.

Documentation

Updated the README to show the new functionality.

[adrielp]

Hey @kevinschoonover -- greatly appreciate the initiative here on opening a PR to help drive things forward! Also happy to see interest and folks contributing to Otel.

I'd love to combine efforts here as I have a local branch that is almost ready, but has a lot of attribute specific things that I've been working with over on the semconv side. Right now, the latest version of semconv available to the collector is 1.27 but there are multiple changes in 1.29 that I've temporarily reimplemented directly in this receiver.

Not sure what the best way to join forces here is, but happy to chat here or on slack.

[kevinschoonover]

Hey @adrielp. Thanks for reaching out - do you have a pointer to your branch where you have this? Im happy to join forces on that branch. Just saw this receiver when I was trying to alert on github action failures and thought Id spend a couple hours implementing this.