Feat: Automate account-like optimization

[dimitrovmaksim]

Resolves #4579

What this PR does:

1. Adds a new materialized view info.table_stats that aggregates statistics from pg_stats for subgraph entity tables, calculating estimated unique entities, total versions, and uniqueness ratio.
2. Adds a optional experimental background job querying the view to find eligible tables and setting the is_account_like flag. The job can be enabled by setting the following env vars

• GRAPH_STORE_ACCOUNT_LIKE_SCAN_INTERVAL_HOURS
• GRAPH_STORE_ACCOUNT_LIKE_MIN_VERSION_COUNT
• GRAPH_STORE_ACCOUNT_LIKE_MAX_UNIQUE_RATIO

3. Updates the ENV vars documentation with the new variables and their usage.