Add interface stubs for new signer implementations

[haydenbaker]

Motivation and Context

Modifications

This commit adds the new Signer interface stubs and poms to respective modules

Testing

$ ./mvnw -pl :http-auth,:http-auth-aws,:http-auth-aws-crt,:http-auth-event-stream clean install -am

• Made sure there were no build errors

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Checklist

• I have read the CONTRIBUTING document
• Local run of mvn install succeeds
• My code follows the code style of this project
• My change requires a change to the Javadoc documentation
• I have updated the Javadoc documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed
• I have added a changelog entry. Adding a new entry must be accomplished by running the scripts/new-change script and following the instructions. Commit the new file created by the script in .changes/next-release with your changes.
• My change is to implement 1.11 parity feature and I have updated LaunchChangelog

License

• I confirm that this pull request can be released under the Apache 2 license

[gosar]

We'll need to add javadocs to the interfaces, but I'm ok to merge these stubs sooner to unblock auth scheme resolution changes I'm working on, and add javadocs when you work on the implementations.

[gosar]

nit: maybe this should use the term "generic", i.e., for generic HTTP services. Also, in these sentences when using http, maybe it should be HTTP.

[haydenbaker]

Yeah, I figured we could add the doc-comments in the follow-up PR for implementation

[sonarqubecloud]

SonarCloud Quality Gate failed.   

3 Bugs
0 Vulnerabilities
0 Security Hotspots
75 Code Smells

49.8% Coverage
3.2% Duplication