Fix the mess with #tableName #columnName #columnAlias

[juliendelplanque]

In PSQLGrammar. Sometimes it is used, sometimes #identifier is used.

#tableName is just an alias to #identifier, it should be removed.

[juliendelplanque]

PSQLGrammar>>#plpgsqlRowTypeDeclaration is still to fix.

[juliendelplanque]

In fact all these methods should be replaced to use #identifier or #identifierWithOptionalFieldAccess.