Update server files in the repo in support of new datasets

[PaulWessel]

This PR updates a few files in the gmtserver repo:

1. It adds cache CPT files for the new data sets: earth_faa.cpt, earth_vgg.cpt, earth_geoid.cpt, earth_mag.cpt, earth_wdmam.cpt and also adds earth_age.cpt which is a duplicate of the age_chrons_GTS2012_2020.cpt file. The CPT files are still kept in the cache as there is no simple way to make a change here yet.
2. It adds/modifies recipes used to build the datasets and tiles.
3. It updates the processing scripts to use /tmp/$$ as temp dir so more than one script can run at the time.

Note 1: This does NOT yet update the _gmt_dataserver.txt file which lists the new data since those are not yet on the oceania server. They have been placed on the test server for now until we decide to release them. Once we have completed some tests via the test server then we will move the new data files to the oceania server and a separate PR will update the _gmt_dataserver.txt file. Within an hour the gmtserver will update its _gmt_dataserver.txt from the repo and then users accessing the server will get a fresh list and suddenly have access to more data.

Note 2: To avoid issues with failing GMT tests, the first data release will not include the Sandwell SRTM/SYNBATH updates. Once we have migrated the test images we will update gmt_data_server.txt to show the two new datasets and also copy these from the test to oceania (and overwrite the old earth_relief grids).

Once this PR is merged I will let the GMT testers know how to test the data via the test server.

[PaulWessel]

Will you be able to get to this one today, @meghanrjones ?