Refactor CI

[antoniovazquezblanco]

This PR refactors the CI of the project:

• Split the process into building natives, building the plugin and releasing
• Build the plugin for all the supported versions of Ghidra, this acts as testing but also provides builds for everyone...
• Use maintained github actions as much as possible to avoid maintaining steps such as downloading and installing Ghidra

Hope it helps!

[al3xtjames]

Thanks for cleaning this up! Overall this looks good, though I ended up making some changes. I'm OK with manually creating releases. It's probably better than my current approach of creating a release for each new commit on master. I'm less certain about supporting older versions of Ghidra - there have been some API changes previously (such as #15 and #20). 10.2 is likely recent enough though, so I'll keep it enabled in CI.

[antoniovazquezblanco]

Thank you!