Create a new reflection code.

[fernape]

• Use typeinfo package name to avoid clashing with Go's reflection package.
• Use a simple map-based cache to store reflection information.
• Info struct holds the relevant reflection information.

• Implement reflection for simple types, structs and sqlair.M.

  A more complete version that allows for setting and getting values is in https://github.com/fernape/sqlairexperiment/tree/minimal-reflection