* removes the lifetime from Row
* removes MySqlQueryAs, SqliteQueryAs, etc. (no longer needed)
* introduce query_scalar
* introduce Decode::accepts to allow overriding runtime type checking
per-type (replaces TypeInfo::compatible)
* introduce Encode::produces to allow overriding the encoded type per-value
* adds a lifetime to Arguments (and introduce the HRTB HasArguments)
to support zero-copy encoding with SQLite
* renames Database::RawBuffer to HasArguments::ArgumentBuffer
* introduce Connect::connect_with to provide an ConnectOptions type
explicitly to opt-out of connection string parsing
* introduce Value and ValueRef traits to allow decoding-deferred
extraction of values from Rows
* introduce Encode::encode_by_ref and change Encode::encode to take
by-value to try and re-use memory where possible
* use thiserror to generate sqlx::Error
* [!] temporarily removes query logging
* [!] temporarily removes transactions
