Move LDAS_App under GEOSldas_GridComp as GEOSldas_App

[mathomp4]

Draft PR to see what happens when Applications/LDAS_App is moved to Components/GEOSldas_GridComp/GEOSldas_App

[gmao-rreichle]

@mathomp4 : Now that GEOSldas Release v18.0.0 is done, we can change the repo structure. My preference is to create only one "GridComp" repo in addition to a fixture repo, as in the present PR. That is, the "GridComp" repo should include the "App" dir.

The only branch that needs translating into the new repo structure is @weiyuan-jiang's branch feature/wjiang/add_landice, which is associated with #705. This branch still needs updating to the current "develop", but I'd prefer that @weiyuan-jiang does the update.

I assume the next step would be for you to put together the new repo structure and PR for real and create a new PR for the change.

Please let me know if you have any questions, thanks!

cc: @biljanaorescanin

[mathomp4]

I'm going to re-do this PR again. The conflicts are just confusing enough I want to do it again carefully.