Make the custom picture selector the default

[nicolas-raoul]

Context

Currently, when tapping + in the main activity, there are 3 options: camera, system picker, custom picker.

It is almost impossible for new users to figure out whether they should tap system picker or custom picker.
They may try the former, be content with it, and never discover the many advantages of the custom picker.

Solution

When tapping + in the main activity, only camera and the custom picker would be available.

Only the system picker has the option to upload from Google Drive/etc, so some users may prefer it.
So we should:

• Add a "Switch to system selector" in the hamburger menu of the custom picker. Tapping it also shows a snack or toast "You can choose the selector in the settings."
• Add an option "Use custom picker" in the app's settings, enabled by default, just above "Use document based photo picker".

[Maykur]

Can I try taking this on? I have a few ideas on making it work!

[ErenratZeng]

Can I quickly implement this and get the issue assign to me? Caz seems Maykur did not done this for a month.

[nicolas-raoul]

@Maykur Anything progress or insights/findings to share? :-)

[nicolas-raoul]

Warning: Actually recently the custom selector currently has some bugs, so even if this pull request is created, we might not merge it before a few month. So it might be better to go for a different issue. Thanks for your understanding!