[FR] Global hooks

[blueset]

Is your feature request related to a problem? Please describe.
Currently there are some needs on modifying the behavior of channels that is not a part of message delivery between them. The current method of doing this kind of stuff is to monkey patch the channel which can lead to compatibility problems.

Some modules/feature requests related:

• efb-middlewares/patch: patches ETM/EWS for some additional features.
• FR by BMWCTO@telegram requesting to upload files to third party when file size limit is exceeded.

Describe the solution you'd like
Design a global hook registration/execution mechanism at the framework (cf. WordPress). Modules (esp. channels) register hook points to the coordinator, and other modules (esp. middlewares) can hook on to the points and modify the outcome value before proceeding.

Additional burden could be added on to module authors to document the hooks. Decision of where to put the hooks could also be difficult.

Describe alternatives you've considered
None by far.

Additional context
N/A.