Add catalog specific tmpdir

Each catalog should have the option to have own tmpdir variable.

• For example, one should be able to define that #tmp, inside the cataog directory should be used to store all temporary files and tables.
  (This would make it easy to see how much space a tenant is using).

Move global mysql_tmpdir to catalogs.tmpdir
(see build_tmptable_filename)

Enabling this feature it will be part of adding support of catalog specific variables