IdDictDetDescrCnv: implemented a mechanism for reading ID dictionaries from SQLite as BLOBs

If GeoModel is initialized from SQLite, then `IdDictDetDescrCnv first attempts to read ID dictionaries from SQLite tables in BLOB format. In case of success, the dictionaries will be written out as XML files into the run directory and passed to the dictionary parser for further processing.

This can be considered an interim solution aimed to avoid making any changes in the ID dictionary parser, and in this way to support several options for ID dictionary initialization:

1. Retrieve ID dictionary file names from Geometry DB tables
2. Retrieve ID dictionary file names from SQLite database tables
3. Retrieve ID dictionaries as BLOBs from SQLite database tables

Later we can consider dropping the step of writing BLOBs on disk as XML files, and instead to pass them as strings to the dictionary parser.