refactor: separate datasource and stores configuration

[ndr-brt]

Feature Request

Currently, the store and the datasource configurations are strictly tied, e.g.:

when a store like the AssetIndex one is configured, the configuration is expected this way:

edc.datasource.asset.name=asset
edc.datasource.asset.url=jdbc...
...

the configuration path would let think that this configuration regards the DataSource, that's true, but this is also telling that the SqlAssetIndex store will connect to the asset datasource, so it is not possible to declare a different DataSource for that store.

The proposal would be to add a config setting for every store like:

edc.sql.store.asset.datasource=datasourcename
edc.sql.store.policydefinition.datasource=another_datasourcename
edc.sql.store.contractnegotiation.datasource=datasourcename

so that for every store will be possible to configure a datasource defined previously, and let default be used by default, so for the majority of cases will be just enough to define a edc.datasource.default datasource and that will work by default for every store.
The edc.datasource.<context>.name could eventually be deprecated.

The refactoring would then go through the AbstractSqlStore, that currently requires both dataSourceRegistry and dataSourceName to be passed but, in fact, the dataSource could be resolved before the store initialization and be passed as a store field: there's no reason to resolve it from the registry every time a connection is needed.

Which Areas Would Be Affected?

sql

Why Is the Feature Desired?

cleanup, developer experience

Solution Proposal

If possible, provide a (brief!) solution proposal.

[github-actions]

This issue is stale because it has been open for 14 days with no activity.