[Feature Request]: Add configuration for SQLCMD mode on / off by default for new query windows.

### Feature Description

I would like the MSSQL extension to be configurable to have SQLCMD mode on or off by default
so that I do not have to enable this for each script that I run with SQLCMD variables

### Problem and Motivation

Currently, I have to connect to a server, wait, and then enable SQLCMD mode in the bottom bar and then can run the script. It would be better if I could just configure SQLCMD mode to be on by default and just run the script, get the connection prompt and then the script runs once the connection is established.

### Related Area

- [x] Connection dialog
- [ ] Query results panel
- [ ] Query editor
- [ ] Object Explorer
- [ ] Table Designer
- [ ] Schema Compare
- [ ] Schema Designer
- [ ] Local container
- [ ] GitHub Copilot integration
- [ ] Query Plan Visualizer
- [ ] Other (please describe below)

### If you selected "Other", please describe the area

_No response_

### Confirmation

- [x] I have searched existing feature requests and couldn't find a match
- [ ] I want to help implement this feature