Added: Add FloatingActionButton and UserFeedback components

[drikusroor]

This pull request adds the FloatingActionButton and UserFeedback components to the project. It also includes various style updates and unit tests.

At the experiment's feedback_info you can supply a parameter to turn it on or off for a given experiment by setting show_float_button to True.

For example:

def feedback_info(self):
        info = super().feedback_info()
        info['show_float_button'] = True
        return info

It currently looks like this:

Screen.Recording.2023-12-28.at.13.57.12.mov

Flow

• User sees floating feedback button in the center right on it and clicks it
• Floating Action Button opens with an animation
• User enters feedback in text input
• User clicks submit
• If successful, a "Thank you..." message is shown
• User can close the Floating Action Button again by clicking the "X" close icon button, or by clicking somewhere else in the screen

Questions for the reviewer(s)

• Should we enable or disable it by default for all experiments?
• Should it look exactly like the existing feedback button on the UvA site in the issue?
• If not, is there anything else you would like to change to the appearance or the behavior of the components?

Resolves #264

[hhoning]

looks great to me!

[BeritJanssen]

Nice! I don't think it will hurt to merge this, but please remove the floating button from gold_msi for now. We should discuss with the researchers which experiments should or should not have the feedback button visible first.