[breaking] pruning and reorganizing fields from protos, moving stuff to state

[heavycrystal]

⚠️ This change can break existing CDC mirrors!

Performs several breaking changes to our protobufs:

1. Removes unused fields from FlowConnectionConfigs: table_schema, src_table_id_name_mapping, table_name_schema_mapping, snapshot_sync_mode, cdc_sync_mode, push_batch_size, push_parallelism, metadata_peer. src_table_id_name_mapping and table_name_schema_mapping are now moved to state, setup from SetupFlow and passed accordingly via more proto changes. Order shuffled around to group similar fields together.
2. Removed unnecessary generalization of table_identifier
3. Removed unused messages EnsurePullabilityInput and EnsurePullabilityOutput
4. Changed wording of do_initial_copy and initial_copy_only to better align with other options.
5. Removed columns from TableSchema and fixed related methods up.
6. batch_size had 3 different datatypes and was being modified in multiple places, making sure batch_size and idle_timeout_seconds has one source of truth.