Inherit the button styles of Blocksy and theme.json

[bfintal]

This replaces issue #2354

1. Add an option in the admin settings: "Use button styles from theme"

• This should be enabled by default
• If updating from an old version, this option should be disabled

2. When the option is enabled, inherit the button styles of Blocksy and/or theme.json. Not all the styles, but only the general ones - that fit our button attributes.

Inherit the ff styles from Blocksy's settings:

• What to inherit:
  • General
    • Min. Height
  • Design
    • Font Color - able to inherit but please double check
    • Background Color - able to inherit but please double check
    • Border
    • Padding
    • Border Radius - able to inherit but please double check

For the theme.json file itself, we would need to follow how styles are used by the native button block (not probably directly reading from the theme.json file).

Expected behavior:

• When adding a button, it should look like adding a native button
• Even though the button looks like the native one, all aspects of the block should can be overridden using the block attributes
• Existing users who already have existing buttons should not be affected after getting this update
• Existing users who enable the "Use button styles from theme" option should have their existing buttons look like the theme's (except if they already have modifications to the button attributes)