Experiment to simplify the API

[ruslandoga]

Changes:

• improve timezone / datetime support

For RowBinary:

clickhouse tz	app tz	value	result
any	any	%DateTime{time_zone: "Etc/UTC"}	dump to unix timestamp
any	any	%DateTime{time_zone: "Asia/Taipei"}	conversion into unix timestamp (this is slow)
UTC	UTC	%NaiveDateTime{}	dump to seconds = unix timestamp (correct)
Europe/Berlin	UTC	%NaiveDateTime{}	dump to seconds = unix timestamp (still correct)
Europe/Berlin	Asia/Taipei	%NaiveDateTime{}	dump to seconds != unix timestamp (incorrect, should raise?)

For queries:

clickhouse tz	app tz	datetime

• automatically decode streams

# decode by default (format=RowBinaryWithNamesAndTypes)
DBConnection.run(conn, fn conn ->
  Ch.stream(conn, "select * from numbers limit {limit:UInt64}", %{"limit" => 1_000_000})
  |> Stream.each(&IO.inspect/1)
  |> Stream.run()
end)
# %Ch.Result{rows: [[]], data: <<>>}
# %Ch.Result{rows: [[]], data: <<>>}
# %Ch.Result{rows: [[]], data: <<>>}

# don't decode unknown format
DBConnection.run(conn, fn conn ->
  Ch.stream(conn, "select * from numbers limit {limit:UInt64} format CSV", %{"limit" => 1_000_000})
  |> Stream.each(&IO.inspect/1)
  |> Stream.run()
end)
# %Ch.Result{rows: nil, data: ''}

# don't decode if `decode: false`
DBConnection.run(conn, fn conn ->
  Ch.stream(conn, "select * from numbers limit {limit:UInt64}", %{"limit" => 1_000_000}, decode: false)
  |> Stream.each(&IO.inspect/1)
  |> Stream.run()
end)
# %Ch.Result{rows: nil, data: <<>>}