Add check in build-namelist_test.pl

[mvdebolskiy]

Description of changes

Added a check in failtest, warntest, finidat_files, so when a new test or finidat file are added and one of the subkeys is misspelled you will get an error and tester will die.

Specific notes

Contributors other than yourself, if any:

@ekluzek

[mvdebolskiy]

You can test this by misspelling a subkey for one of the existing ones.

[mvdebolskiy]

Fixes #2673