When pasting HTML, we have to be careful not to introduce invalid HTML.
The editor corrected for blocks within inlines but failed to prevent the
invalid pasting of blocks within paragraph-related elements
(eg., `<p><h1>text</h1></p>`). This fixes that issue by unwrapping all
blocks from the copied content when trying to paste within an element
that doesn't accept paragraph-related elements as children.
Notably, this fixes an issue that was caused by that problem, in which
pasted HTML content could not be saved because it was invalid.
task-2632676
closesodoo/odoo#79070
X-original-commit: 9c77834e03516f831a9600f0ba4131c957b3ba74
Signed-off-by: David Monjoie (dmo) <dmo@odoo.com>