Added new optional param to [p]muteset senddm for auto unmute dm

[turbo-jayce]

Description of the changes

• Added a new variable dm_auto_unmute as a toggle
• senddm has new optional parameter that can toggle dm's off for auto unmutes
• if parameter isnt specified it will default to value inputted to setdm
• allows for dm's to be sent for mutes, and no dm's sent for when they are automatically unmuted

Have the changes in this PR been tested?

No

Additional Notes

This is my first PR to repo and unsure if this is the proper way to go about this.

Issue

Closes #6262

[Flame442]

I know this is still a draft, but here's some tips about what is currently missing to get you on the right track:

• You need to make a config call to get the value of dm_auto_unmute before it can be used as a value.
  • It might make sense to move these checks within _send_dm_notification by adding a parameter specifying whether it was called for an auto unmute or a manual unmute.
• Rather than adding to the existing command, you should probably make a separate command for configuring this new setting.
• You need to use the black autoformatter to style the updated code, in accordance with the CONTRIBUTING.MD file.

[Kowlin]

Due to the lack of activity on this PR, I'm gonna go ahead and close this.