This fixes all kinds of problems related to missing params,
like broken timestamps (due to `integer_datetimes`).
This solution is not ideal, but it will help. Meanwhile,
I'm going to dedicate some time to improving connection machinery.
Note that this **does not** fix problems with passing certain parameters
in a reverse direction, i.e. **from client to compute**. This is a
separate matter and will be dealt with in an upcoming PR.
Downsides are:
* We store all components of the config separately. `Url` stores them inside a single
`String` and a bunch of ints which point to different parts of the URL, which is
probably more efficient.
* It is now impossible to pass arbitrary connection strings to the configuration file,
one has to support all components explicitly. However, we never supported anything
except for `host:port` anyway.
Upsides are:
* This significantly restricts the space of possible connection strings, some of which
may be either invalid or unsupported. E.g. Postgres' connection strings may include
a bunch of parameters as query (e.g. `connect_timeout=`, `options=`). These are nether
validated by the current implementation, nor passed to the postgres client library,
Hence, storing separate fields expresses the intention better.
* The same connection configuration may be represented as a URL in multiple ways
(e.g. either `password=` in the query part or a standard URL password).
Now we have a single canonical way.
* Escaping is provided for `options=`.
Other possibilities considered:
* `newtype` with a `String` inside and some validation on creation.
This is more efficient, but harder to log for two reasons:
* Passwords should never end up in logs, so we have to somehow
* Escaped `options=` are harder to read, especially if URL-encoded,
and we use `options=` a lot.