Include ExpandableBottomSheetController

[alestiago]

Description

Use ExpandableBottomSheetController instead of key to manage the state of the ExpandableBottomSheet.

[alestiago]

@torbenkeller I can work on this issue. Let me know if you agree with this change, since this can include a breaking change to the current API.

[torbenkeller]

Sorry for the late reply. I think a ExpandableBottomSheetController would be a better interface so feel free to work on this :)

[alestiago]

@torbenkeller , I started working on the implementation of the ExpandableBottomSheetController. Let me know your thoughts about #15 , which is currently under development.

[Kinomad]

Hi, congratulations for you great job :)
Can be very nice and useful to have an ExpandableBottomSheetController, especially to get and control the offset of the ExpandableBottomSheet. Impatient to get this new feature, do you have an idea when it should be available?
Thanks for your work !

[alestiago]

Hi @Kinomad thank you for the feedback, it means a lot! 💙

I'm not sure when the feature will be finished. I've already started working on it, you can check the PR #15 . Feel free to make a code review and leave some feedback about it, I would really appreciate it 😄