[FIX] web editor: cursor jumps out of blockquote

Steps to reproduce:

1. add a paragraph
2. add a blockquote
=> the cursor will jump in the paragraph
This commit fixes a bug detected when inserting a blockquote. The cursor
jumps to nearby paragraph on insert, and other issues.

The cause of the bug is tied to the fact that we rely on a complex behavior
when inserting paragraph related elements (within the insert command).
The way to make blockquote behave like the other paragraph related
elements is simply to add it to the list as done in this commit.

Task-3383441

closes odoo/odoo#134633

X-original-commit: 8195beac
Signed-off-by: David Monjoie (dmo) <dmo@odoo.com>