Drop support for iterators where they are not needed (#969)

* delete_messages: Drop support for generators

Since we used a list there anyway, this approach will lead to more localized errors and can reduce function overhead.

Signed-off-by: devops117 <55235206+devops117@users.noreply.github.com>

* delete_messages: Return pts_count:int

An example usecase would be for a normal bot which uses range based on message ids
instead of keeping a track of messages and using the DeletedMessagesHandler.

Signed-off-by: devops117 <55235206+devops117@users.noreply.github.com>

* Drop support for Iterators and update docstrings and some cleanups.

Signed-off-by: devops117 <55235206+devops117@users.noreply.github.com>

* Update get_users.py

* Update get_messages.py

* Update delete_messages.py

* Update forward_messages.py

* Update get_messages.py

Co-authored-by: Dan <14043624+delivrance@users.noreply.github.com>