Display errors in UI correctly when creating notes

What does this MR do and why?

• Resolves sub-task 1 of https://gitlab.com/gitlab-org/gitlab/-/issues/411329
• Fixes the way that UI handles validation errors when adding a note or when replying to a discussion
• It displays the error message above the problematic note and returns the input back to the note-form
• This is a pre-condition to the epic (https://gitlab.com/groups/gitlab-org/-/epics/10118) where we would add a validation error to the note when it gets detected as spam.

Screenshots or screen recordings

Context	Before	After
adding a note	adding-note-before	adding-note-after
adding a note (snippet i.e. deprecated_notes.js)	adding-deprecated-note-before	adding-deprecated-note-after
replying to discussion	replying-to-discussion-before	replying-to-discussion-after

How to set up and validate locally

1. Add a validator to the app/models/note.rb model since we don't have an easy validation we can test against in the Note model.

validate :test_ui_validation, on: [:create, :update]

def test_ui_validation
    if note.include? 'TEST_VALIDATION'
      self.errors.add(:base,  _('it failed validation'))
    end
end

2. Navigate to any issue / merge request / snippet / commit and add a note with TEST_VALIDATION.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #411329