Sql: Improve bootstrap performance by getting all the metadata information in one go from the db

In `SqlMetadataProvider`, we use different methods to collect metadata information from the underlying database object source:
1) a DbDataAdapter to get table columns, their type, and primary key
2) GetSchema on Columns to find out if each column has Default value or not.
3) Use a ForeignKey Query to derive the referenced table, and the referenced columns.

This involves multiple round trips to the database.
This issue is to investigate if we can optimize this bootstrap to acquire all this information in a single roundtrip.

Iniziate individuando SqlMetadataProvider e tracciando i percorsi di DbDataAdapter, GetSchema su Columns e ForeignKey Query. Determinate se il database può fornire insieme colonne, tipi, chiavi primarie, valori predefiniti e riferimenti a chiavi esterne, quindi verificate che il bootstrap preservi tutti i metadati riducendo a uno i round trip al database.

Scritto dal modello di indicizzazione a partire dal testo della issue.