Add missing pre built analysis components
closes #6770
Remove intern calls on FieldMapper#Names
remove internal callas on FieldMappers#Names, we properly reuse FieldMapper, so there is no need to try and call intern in order to reuse the names. This can be heavy with many fields and continuous mapping parsing.
closes #6747
[API SPEC] Update indicies.stats group param
add more options to many mappings test
[ENGINE] Prevent NPE if engine is closed while version map is checked

We check if the version map needs to be refreshed after we released
the readlock which can cause the the engine being closed before we
read the value from the volatile `indexWriter` field which can cause an
NPE on the indexing thread. This commit also fixes a potential uncaught
exception if the refresh failed due to the engine being already closed.

Relates to #6443
Closes #6786