PostgreSQL wire-compatible API

[jeromegn]

Exposes a PostgreSQL wire compatible API

It works like this:

• Decodes "Frontend" PG messages
• Encodes "Backend" PG messages
• Implements the flow as best as possible (described at Message flow)
• Parses the current SQLite schema to figure out the types of each column in each table
• Parses every command w/ sqlite3-parser
• Attempts to figure out the types fo each bound parameter and returned columns

Tested w/ Rust's tokio-postgres client.

Manually tested w/ Elixir's Ecto and Golang's database/sql.