feat: create this plugin (and add semantic-release to CI)

[kieckhafer]

This plugin replaces the internal notifications package that is currently in Reaction. It has not been tested by anyone aside myself yet, so although the changes in this particular PR only enable semantic release, please test the full functionality of the plugin before approving.

Once this PR is merged and this plugin is published to npm, there will be a related PR in reaction to swap out this plugin for the existing version.

Testing

• npm link this PR into the Reaction API
• remove the existing src/plugins/notifications/ folder to delete the current version of this plugin
• update registerPlugins.js inside of Reaction API to use the npm version of this package
• Start Reaction, see you can use the createNotification mutation

[rc-publisher]

:tada: This PR is included in version 1.0.0 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: