extractor: Setup signing and publishing for CI snapshots

[theimpulson]

Summary

This PR:

• Sets up signing and publishing for CI snapshots on Maven Central

Guidelines

• I carefully read the contribution guidelines and agree to them.
• I have tested the API against NewPipe.
• I agree to create a pull request for NewPipe as soon as possible to make it compatible with the changed API.

[theimpulson]

I couldn't verify the publishing as the secrets seems to be only available to a protected branch (?)

[TobiGr]

I setup a minimal branch protection rule
@Stypox set the variables. so he might know more.

The workflow is only running on dev, so it won't run here.

[theimpulson]

The workflow is only running on dev, so it won't run here.

I need permission to push to the current snapshot branch without a PR or by force push to test changes as now its protected.

[TobiGr]

I removed the branch protection rule

[Stypox]

Thank you!

[theimpulson]

Seems to be working fine, so I will go ahead and remove the branch from the workflow file to limit it to dev and manual trigger.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[Stypox]

Thank you! This can be merged from my side! Maybe let's wait for @TobiGr to confirm

[TobiGr]

I think we can go ahead and test it