add Object actions

[TCMine]

Please describe the changes this PR makes and why it should be merged:

These actions allow working with JSON Objects easily.

Status

• [x] Code changes have been tested against the Discord API and the discord.js wrapper, or there are no code changes
• [x] Documentation has been added/modified, or there is nothing to change (docs/mods.json)

Semantic versioning classification:

• [ ] This PR changes DBM's interface (methods or parameters added to default methods)
• [ ] This PR only includes non-code changes, like changes to documentation, README, etc.

--> Please feel free to propose name change suggestions for the actions because I'm not so sure about them.