feat: add SSH configuration support for DB2 and MSSQL drivers

[siiddhantt]

Description

Adds SSH tunnel support for DB2 and MSSQL drivers, matching the existing pattern used by Postgres, MySQL, MongoDB, and Oracle.

• DB2: Uses a local TCP proxy since go_ibm_db (CGO) has no Go-level dial hook — listens on localhost:0 and forwards through the SSH client.
• MSSQL: Uses go-mssqldb's Connector.Dialer + HostDialer interfaces to route connections through the SSH tunnel (DNS resolves on the remote side).

Fixes #814

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

• MSSQL SSH tunnel e2e — check and discover via password and key auth through Docker SSH bastion (MSSQL container with no host-exposed ports, reachable only through tunnel)
• Unit tests — 11 MSSQL + 9 DB2 config tests

Documentation

• Documentation Link: [link to README, olake.io/docs, or olake-docs]
• N/A (bug fix, refactor, or test changes only)

[nayanj98]

@siiddhantt Please upload a video of your work and running the sync with OLake. As soon as this is provided I can assign a reviewer.

[siiddhantt]

@nayanj98 thanks, I've attached a video of running the sync in Slack btw

[nayanj98]

@siiddhantt Thanks a lot. Will try to assign a reviewer as soon as possible.