[receiver/postgresql] Add More Table Metrics

[schmikei]

Is your feature request related to a problem? Please describe.
Looking to add these metrics:

• postgresql.database.count
• postgresql.table.count
• postgresql.table.size
• postgresql.table.vacuum.count

Describe the solution you'd like
Adds a top level metric for the number of databases: postgresql.database.count

Adds a database level metric for number of tables: postgresql.table.count

Adds two metrics for tables: postgresql.table.size and postgresql.table.vacuum.count

Describe alternatives you've considered
Plan is to hide behind the receiver.postgresql.emitMetricsWithResourceAttributes featuregate.

Additional context
Initial Issue #12338

[schmikei]

I will be working on this