feat(db-postgres): allow to store blocks in a JSON column (#12750)

Continuation of https://github.com/payloadcms/payload/pull/6245.
This PR allows you to pass `blocksAsJSON: true` to SQL adapters and the
adapter instead of aligning with the SQL preferred relation approach for
blocks will just use a simple JSON column, which can improve performance
with a large amount of blocks.

To try these changes you can install `3.43.0-internal.c5bbc84`.

packages/db-vercel-postgres/src/index.ts

@@ -95,6 +95,7 @@ export function vercelPostgresAdapter(args: Args = {}): DatabaseAdapterObj<Verce
       afterSchemaInit: args.afterSchemaInit ?? [],
       allowIDOnCreate,
       beforeSchemaInit: args.beforeSchemaInit ?? [],
+      blocksAsJSON: args.blocksAsJSON ?? false,
       createDatabase,
       createExtensions,
       defaultDrizzleSnapshot,

packages/db-vercel-postgres/src/types.ts

@@ -33,6 +33,10 @@ export type Args = {
    * To generate Drizzle schema from the database, see [Drizzle Kit introspection](https://orm.drizzle.team/kit-docs/commands#introspect--pull)
    */
   beforeSchemaInit?: PostgresSchemaHook[]
+  /**
+   * Store blocks as JSON column instead of storing them in relational structure.
+   */
+  blocksAsJSON?: boolean
   connectionString?: string
   /**
    * Pass `true` to disale auto database creation if it doesn't exist.