Larger rate limit integers (#16047)

Tokens per day may exceed the range of Postgres's 32-bit `integer` data
type.

Release Notes:

- N/A

Co-authored-by: Marshall <marshall@zed.dev>

crates/collab/migrations_llm/20240809130000_change_rate_limit_columns_to_bigint.sql

@@ -0,0 +1,4 @@
+ALTER TABLE models
+    ALTER COLUMN max_requests_per_minute TYPE bigint,
+    ALTER COLUMN max_tokens_per_minute TYPE bigint,
+    ALTER COLUMN max_tokens_per_day TYPE bigint;