Remove deprecated and unused functionalities in deegree console

[julianzz98]

The following functionalities of the deegree administration console are considered deprecated and seem to be unused by the community:

• Import GML feature collections ("Loader")
• Import metadata sets ("Loader")
• Create database tables ("Setup tables")

I am proposing to remove them from the console and the codebase.
The references to the named functionalities were already removed with PR #1763.

[julianzz98]

It needs to be investigated, if the functionality of the button "Setup tables" is actually working after the fix introduced in #1703.

[julianzz98]

Adjustments of the changes introduced with #1763 will be made after the functionality is tested again.

[julianzz98]

The functionality was successfully tested locally using the deegree 3.6.0-pre3 Docker image. A preconfigured workspace from the deegree-workshop was used for the test. The existing schemas in the database were deleted, and new schemas were created using the "Setup tables" button. After, the data was imported using the GmlLoader:

docker exec -w /opt deegree_3.6 java -Xmx16g -jar deegree-tools-gml.jar GmlLoader -pathToList=/root/.deegree/ps-sl/data/gmlData/gmldatalist.txt -workspaceName=ps-sl -sqlFeatureStoreId=INSPIRE_ProtectedSites_WFS  

Once the GmlLoader completed its run, a WFS GetFeature request was successfully executed, returning data as expected.

As the next step, the documentation needs to be updated to include a description of this functionality.
It should be mentioned that the "Turn on highlighting" button does not work.