fix(webhook): specify permitted auth subclasses explicitly to stabilize template generation

[chillleader]

Description

This PR defines the list of permitted subclasses of the webhook authentication interface explicitly. Previously it has been derived implicitly because subclasses were in the same file, but in the byte code the order was not fixed, which lead to flaky template generation results and auth option reordering in the element templates.

[github-actions[bot]]

Backport failed for release/8.3, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin release/8.3
git worktree add -d .worktree/backport-2775-to-release/8.3 origin/release/8.3
cd .worktree/backport-2775-to-release/8.3
git switch --create backport-2775-to-release/8.3
git cherry-pick -x 5f93d4ad6f9ee93a2f750c151f2cf713fffda026

[github-actions[bot]]

Backport failed for release/8.4, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin release/8.4
git worktree add -d .worktree/backport-2775-to-release/8.4 origin/release/8.4
cd .worktree/backport-2775-to-release/8.4
git switch --create backport-2775-to-release/8.4
git cherry-pick -x 5f93d4ad6f9ee93a2f750c151f2cf713fffda026

[github-actions[bot]]

Successfully created backport PR for release/8.5:

• 2785

[chillleader]

/backport

[github-actions[bot]]

Successfully created backport PR for release/8.6:

• 2788