Query layer: support ssh fields, sync interval, simplify code path

[Amogh-Bharadwaj]

• Adds parsing for SSHConfig fields in Create Peer command for Postgres

CREATE PEER postgres_peer FROM POSTGRES WITH
(
    host = '<hostname>',
    port = 5432,
    user = '<user>',
    password = '<password>',
    database = '<dbname>',
    ssh_config = '{
        "host": "<ssh_host>",
        "port": 22,
        "user": "<ssh_user>",
        "password": "<ssh_password>",
        "private_key": "<ssh_private>"
    }'
);

• Also you can now specify sync_interval in the create mirror command

• Remove catalog flows table entry and update operations in query layer side, as we are anyways hitting a grpc endpoint which takes care of that. This makes the create_catalog_entry flag in the request to create/validate mirror endpoints redundant, so that is removed from route.proto

• Fixes a bug in validate mirror where select * from sourcetables limit 0 was not checked for empty publication

Functionally tested via query layer and UI

[serprex]

this looks like something easy to screw up in future, ideally it'd be a model that returns by value so zero value is correct response. should try make code work with errors returning nil

[Amogh-Bharadwaj]

Will change the validate peer and mirror endpoints in a follow up PR to be something like

func (h *FlowRequestHandler) ValidateCDCMirror(
	ctx context.Context, req *protos.CreateCDCFlowRequest,
) protos.ValidateCDCMirrorResponse {

where the response has an error message field