Add CI and initial python loader/updater

[dzervas]

The build action now:

• Doesn't require a binary ninja license
• Builds the binaries for all platforms
• If triggered manually, bumps the plugin's version
• Updates plugin.json longdescription from readme
• Creates a tag & release

A plugin.json and init.py were also added, however init assumes that in its path the binaries exist which as I understand it binja doesn't do - it just downloads the source of the plugin from the release

init needs to connect to github, find the latest release and download the correct binary - we can do that later

[emesare]

Thank you for taking the time to do this! For an initial loader this looks fine, however in the future it would be best to version with the ABI so that older binary ninja installs don't accidentally download a newer version on an unsupported ABI (and vice-versa).