WL#8662: Deprecate and remove "Delphi style" column and table syntax

Affects: Server-8.0   —   Status: Complete

The parser supports old Deplhi style syntax for columns and table names:

* .column_name

* .table_name.column_name

* .table_name

I.e. dot sign followed by the column/table name.

The first syntax (".col_name") and the second one (".table_name.column_name")
doesn't seem to be documented at all.

The third syntax (".tbl_name") is documented at
http://dev.mysql.com/doc/refman/5.7/en/identifier-qualifiers.html :

: The syntax .tbl_name means the table tbl_name in the default database.
: This syntax is accepted for ODBC compatibility because some ODBC programs
: prefix table names with a “.” character.

Conclusion: it would be nice to remove the .column_name syntax in 8.0.

Reasoning: the syntax is undocumented and most likely unused.

**User Documentation**

* https://dev.mysql.com/doc/relnotes/mysql/5.7/en/news-5-7-20.html
* https://dev.mysql.com/doc/relnotes/mysql/8.0/en/news-8-0-2.html
* https://dev.mysql.com/doc/refman/5.7/en/identifier-qualifiers.html
(deprecation notice)
* https://dev.mysql.com/doc/refman/8.0/en/identifier-qualifiers.html (removal of
deprecated syntax)