feat: servlet classes that use the jakarta namespace

[suztomo]

Fixes #1112, to support the jakarta.servlet namespace.

• In addition to the namespace upgrade, the author, @since, and copyright year are updated.
• The jakarta.servlet-api version 5 is declared as provided dependency. It's 5 (not the latest 6) because this repository is built with Java 8 and version 6 requires Java 11. It's "provided" scope because the servlet API artifacts in general are provided by the runtime (such as AppEngine).
• The corresponding existing classes don't have tests. So I didn't add tests.
• I ran my sample app using these classes and it worked. (work log)

[meltsufin]

@ludoch PTAL

[suztomo]

Do we need to update any public documentation?

Yes, I'll update the document (https://developers.google.com/api-client-library/java/google-api-java-client/oauth2#web_server_applications).