Send the loader embed on heavy commands instead of only calling "typing" event

[koloml]

Is your feature request related to a problem? Please describe.
There is an issue with commands like "top" requiring a lot of time to process before bot is able to print the results. Right now we have bot sending "Typing" event to indicate that request is accepted and in processing:

• Added typing event sending to the channel for top command #102

Since typing event isn't being sent continuously, it feels like bot will not respond at all.

Describe the solution you'd like
Embed with some "Loading" text will be much better for UX. This embed will for sure indicate that bot have accepted the request and generating the response.

Describe alternatives you've considered
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Additional context
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