Add bindParameterName for accessing SQL query parameter names

[nurpax]

• Add a access prepared statement's bound parameter names.
• Add tests for the above

My use-case for this feature can be found here: https://github.com/nurpax/sqlite-simple/issues/5

Note: I realize this is using the String type too. It's probably better to get this code in first, decide whether to use ByteStrings or Text, and then convert the entry points to the new type in one go.

[IreneKnapp]

Looks good. I agree with your rationale. Merging this.