Add Custom Categories

[hlargen5]

As a user, I would like to create new custom categories, edit their names later, and delete entire categories to enhance the customization of my experience.

Acceptance Criteria:

• To add a new category, the user will tap the "plus" icon in the top right-hand corner of the Categories screen. This will take them into the add keyboard flow. New categories will be added to the bottom of the categories list, and should appear on the home screen.
• If a user closes the keyboard without saving, they should receive the discard edits alert.
  - To edit a custom category name, the user will navigate to the category detail screen and tap the pencil icon. This will take them into the edit keyboard flow.
• If a user closes the keyboard without saving any changes, they should receive the discard edits alert.
• If a user does not make any changes and closes the keyboard, no alert should be given.
• To delete an entire category, a user should navigate to the custom category detail screen and tap the trash can icon in the top right-hand corner. This will delete the entire category and all of its custom phrases in both the Categories setting screen and the home screen.
• A user should receive the "are you sure you want to delete?" alert when tapping the delete category button.

Test Note:
Custom Category labels will be in english only for this ticket.

Design:

https://www.figma.com/file/mNrwUygVhTmuWnKNHHkenR/Vocable-New?node-id=1%3A1344

[stevefosterwta]

I created #390 for the editing and deleting of a custom categories.

[SashankPatel]

Implemented on PR391