Selectors::keyValueStringToArray()

Simple "a=b, c=d" selector-style string conversion to associative array, for fast/simple needs

• The only supported operator is "=".
• Each key=value statement should be separated by a comma.
• Do not use quoted values.
• If you need a literal comma, use a double comma ",,".
• If you need a literal equals, use a double equals "==".