fix text and char column php code args

[cfebs]

#39 started setting character_set and collation properties which surfaced a problem that already existed in src/Schema/Column/TextTrait.php

A leading comma would be added to the generated constructor:

php-mysql-engine/src/Schema/Column/TextTrait.php

Line 14 in 2e8b092

? ', \'' . $this->character_set . '\'' . ', \'' . $this->collation . '\''

Also noticed a potential bug in #39 in CharacterColumn arg building:

php-mysql-engine/src/Schema/Column/CharacterColumn.php

Lines 70 to 76 in 21a606f

	return '(new \\' . static::class . '('
	. $this->max_string_length
	. ($this->character_set !== null ? ', \'' . $this->character_set . '\'' : '')
	. ($this->collation !== null ? ', \'' . $this->collation . '\'' : '')
	. '))'
	. $default
	. $this->getNullablePhp();

If only collation was defined in that implementation, the value of collation would be used for the character_set argument in the constructor

This PR:

• just use a simple implode to always pass the number of args for CharacterColumn or TextColumn
• add a test table with each permutation of test and varchar CHARACTER SET and COLLATE