✨ [REQUEST] Transmission - set config directory from configuration page

[akslow]

Checked

• [X] If a new addon, I have checked on Google that such as addon doesn't already exists
• [X] If a new feature, I have searched in the discussions & issues that it was not already covered

Which addon?

Transmission = Current version: 4.0.3-r3-ls186

Is your feature request related to a problem? Please describe

Could you add option to set custom config directory for transmission on configuration page- config_dir

Describe the solution you'd like

I would like to have configuration and pending torrents on external drive