chrono::DateTime<FixedOffset> doesn't store the offset (timezone) in sqlite as text and timezone information is lost

[05storm26]

Currently a chrono::DateTime<FixedOffset> in the Encode trait for sqlite is converted to UTC and stored without an offset.

This causes the timezone/offset information to be lost. SQLite supports timezones in its formats: https://www.sqlite.org/lang_datefunc.html#time_values

We should instead store DateTime<FixedOffset> by converting them to RFC3339 format which is a variant of ISO8601 and SQLITE compatible format (using to_rfc3339_opts) and has time offset information in it.

Similarly we should try to utilize this offset in potentially in the text value in the Decode implementation of DateTime<FixedOffset> by first attemting to use DateTime::parse_from_rfc3339.