* 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>
