Merge device_verification from Chethan2k1/mtxclient

* Fix build Issue in the crypto_bot.cpp

* Add Linting

* Change the location of DeviceEventVistor

* Fix to_device test

* Remove iostream header

* Fix Remaining Tests

* Remove Sender and Type in KeyRequest

* Add endpoint to construct to_device messages

* Add new endpoint new_send_to_device

* Made Changes in new to_device_send

* Wait for carl's access_token

Partial update of models.  Tests are still broken and there are some other issues that need to be resolved.  Getting this uploaded so that @Chethan can take a look at what's changed and modify their proposal

This at least partially addresses #3.  I have a feeling that
additional updates will be needed at some point, but this
fixes the issue where mtxclient would throw an exception for
unrecognized event id formats, which caused nheko to crash.

That's what the README suggests and - more importantly - the cmake
config file works with.
Also use angle brackets instead of quotation marks in two cases.