Remove support for useEmbeddedTomcat, tomcat-lib, and log4j2.xml

[labkey-adam]

Rationale

No need to handle standalone builds

[labkey-susanh]

I think there are some methods and/or properties that

[labkey-tchad]

We can probably get rid of the entire distributionResources directory and any tasks that publish it. The distributionResources/embedded is just an incomplete duplicate of server/configs/webapps/embedded. The files here are only used if the corresponding files from the server repo are missing -- which should never happen. Everything else in distributionResources is for standalone tomcat.

[labkey-susanh]

Might still be able to clean up that TomcatExtension, but I'm going to leave that for Trey to answer (and we can do it later if we find it's not used).