fix(drizzle): enforce uniqueness on index names (#8754)

Fixes https://github.com/payloadcms/payload/issues/8752

Previously, trying to define a config like this:
```ts
{
  type: 'text',
  name: 'someText',
  index: true,
},
{
  type: 'array',
  name: 'some',
  index: true,
  fields: [
    {
      type: 'text',
      name: 'text',
      index: true,
    },
  ],
}
```

Lead to the error:
```
Warning  We've found duplicated index name across public schema. Please rename your index in either the demonstration table or the table with the duplicated index name
```

Now, if we encounter duplicates, we increment the name like this:
`collection_some_text_idx`
`collection_some_text_1_idx`

---------

Co-authored-by: Dan Ribbens <dan.ribbens@gmail.com>

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

@@ -90,6 +90,7 @@ export function vercelPostgresAdapter(args: Args = {}): DatabaseAdapterObj<Verce
       fieldConstraints: {},
       getMigrationTemplate,
       idType: postgresIDType,
+      indexes: new Set<string>(),
       initializing,
       localesSuffix: args.localesSuffix || '_locales',
       logger: args.logger,