[FW][FIX] clipboard: don't open composer on firefox

[fw-bot]

Steps to reproduce:

• open a spreadsheet with firefox
• copy a cell
• paste it somewhere else => the composer is open with the pasted content.

Ok... that's weird, but not a big deal.
But it gets better:

• copy multiple cells
• paste them somewhere else => boom

The composer opens in the same way, but it doesn't support multiline text!

This commit fixes the composer opening and it also makes the edition plugin more robust by removing any carriage return that could slip through.

Additional small fix in the content editable helper, the selection start was not clipped if it was greater than the content length.

Note: it doesn't happen on Chrome because ev.data is null when pasting content. It doesn't correctly implements the spec
https://w3c.github.io/input-events/#dfn-data

opw-3236303

opw : 3236303

review checklist

• feature is organized in plugin, or UI components
• support of duplicate sheet (deep copy)
• in model/core: ranges are Range object, and can be adapted (adaptRanges)
• in model/UI: ranges are strings (to show the user)
• undo-able commands (uses this.history.update)
• multiuser-able commands (has inverse commands and transformations where needed)
• new/updated/removed commands are documented
• exportable in excel
• translations (_lt("qmsdf %s", abc))
• unit tested
• clean commented code
• track breaking changes
• doc is rebuild (npm run doc)
• status is correct in Odoo

Forward-Port-Of: #2254
Forward-Port-Of: #2251

[robodoo]

Pull request status dashboard.

[fw-bot]

@LucasLefevre @rrahir cherrypicking of pull request #2251 failed.

stdout:

Auto-merging src/components/composer/content_editable_helper.ts
CONFLICT (content): Merge conflict in src/components/composer/content_editable_helper.ts
Auto-merging src/components/grid/grid.ts
Auto-merging src/plugins/ui_stateful/edition.ts
Auto-merging tests/components/composer.test.ts
Auto-merging tests/plugins/edition.test.ts

stderr:

09:48:29.310323 git.c:455               trace: built-in: git cherry-pick c5610392a565947e1b202890be64c39a8d4cb3fc
error: could not apply c5610392... [FIX] clipboard: don't open composer on firefox
hint: After resolving the conflicts, mark them with
hint: "git add/rm <pathspec>", then run
hint: "git cherry-pick --continue".
hint: You can instead skip this commit with "git cherry-pick --skip".
hint: To abort and get back to the state before "git cherry-pick",
hint: run "git cherry-pick --abort".
----------
status:

Either perform the forward-port manually (and push to this branch, proceeding as usual) or close this PR (maybe?).

In the former case, you may want to edit this PR message as well.

[LucasLefevre]

robodoo r+

[LucasLefevre]

robodoo r+