* clarify that cannot show create table of system's tables
* clarify that cannot show create table of system's tables in the document
* bypass test style-check for required `database=currentDatabase()` because `show create table` do not have condition
* rename supportsShowCreateTable to isSystemStorage
* build fake create query for show create table of system's tables
* fix tests for show create table on system's table:
1. only build fake create query when cannot get real query
2. only test rocksdb when it's enabled.
* fix test for show create table system.tables
* fix test for ASTCreateQuery set table and database
* change to LOGICAL_ERROR when cannot get in_memory metadata
Co-authored-by: tavplubix <tavplubix@gmail.com>
* implement common getCreateQueryFromStorage
Co-authored-by: tavplubix <tavplubix@gmail.com>
1. Dropped support for DatabaseOrdinary for MaterializeMySQL. It
is marked as experimental, and dropping support makes the code
more maintaible, and speeds up integration tests by 50%.
2. Get rid of thread name logic for StorageMaterializeMySQL wrapping,
use setInternalQuery instead (similar to MaterializedPostgreSQL).
This will reduce amount of data that may be lost at shutdown.
v2: replace dynamic_cast with IStorage::isBuffer (@kitaisreal)
v3: replace IStorage::isBuffer with IStorage::flush (@alexey-milovidov)
v4: flush() for StorageProxy/StorageTableFunction
