[Mobile] Modified More block to be read-only

[etoledom]

gutenberg-mobile side PR: wordpress-mobile/gutenberg-mobile#1079

As mentioned in wordpress-mobile/gutenberg-mobile#859 (comment), I opted for modifying the More block to be read only, in order for it to be ready for the next release.

I did a fast test using RichText. It does work well on iOS, but it had some alignment issues on Android, that would need native code to be fixed. It also had a visual glitch on split.

Fixing those issues on Android, it looks promising to use RichText to make this component editable.
Alternatively, we might also want to think on a simpler PlaneText component that we can manipulate at the native level for these cases.

On the design side, I noticed on web that More block and Page Break block look the same, so I implemented the same design we use for Page Break on mobile too.

To test:

• Run the app.
• Search for the Read More block in the example content (or add one if it's a new post)
• Check that it's not editable.
• Check that it can be selectable by tapping anywhere in the block.
• Paste this in the HTML mode:

<!-- wp:more {"customText":"Read more custom from web"} -->
<!--more Read more custom from web-->
<!-- /wp:more -->

• Go back to Visual mode.
• Check that it shows custom content.

[koke]

Should this be "Read more block"? More feels a bit ambiguous

[etoledom]

Modified the accessibility config based on wordpress-mobile/gutenberg-mobile#937

Now all blocks will have a default label based on the gutenberg-defined block name.

[koke]

Looking 😍 to me

[etoledom]

Thank you!