Add Permission Granting on Tables/Schemas for Lakebase Client

[jennsun]

#254

user api experience:

app_sp = "app-sp-uuid"

client.grant_schema(
    grantee=app_sp,
    privileges=[SchemaPrivilege.USAGE, SchemaPrivilege.CREATE],
    schemas=["drizzle", "ai_chatbot", "public"],
)

client.grant_all_tables_in_schema(
    grantee=app_sp,
    privileges=[TablePrivilege.SELECT, TablePrivilege.INSERT, TablePrivilege.UPDATE],
    schemas=["drizzle", "ai_chatbot"],
)

client.grant_table(
    grantee=app_sp,
    privileges=[TablePrivilege.SELECT, TablePrivilege.INSERT, TablePrivilege.UPDATE],
    tables=[
        "public.checkpoint_migrations",
        "public.checkpoint_writes",
        "public.checkpoints",
        "public.checkpoint_blobs",
    ],
)

Confirmed permission granting works via SDK and then querying in lakebase what permissions are available: