Pass all uknown parameters to jdbc url string

### Feature description

_Not sure if bug or feature_

I'm using hikari and postgresql. You can pass additional params via ugly jdbc URL:
```
datasources:
default:
url: jdbc:postgresql://localhost:5432/db?-c%20my.var=SOMEVAL%20-c%20pg_trgm.similarity_threshold=0.1
```
I assumed that I can do instead
```
datasources:
default:
url: jdbc:postgresql://localhost:5432/db
options: -c my.var=SOMEVAL -c pg_trgm.similarity_threshold=0.1
```
or even better
```
datasources:
default:
url: jdbc:postgresql://localhost:5432/db
options:
- -c my.var=SOMEVAL
- -c pg_trgm.similarity_threshold=0.1
```
and all unknown params will be url encoded and attached to jdbc url but It doesn't work.

Start by tracing how datasources.default.options is bound and how the Hikari JDBC URL is assembled; inspect existing datasource configuration tests. Done means unknown options are URL-encoded and appended to the PostgreSQL JDBC URL, including both the scalar and list forms shown in the issue.

Written by the indexing model from the issue text.