Migrate `form_errors` in app/views/admin/identities/_form.html.haml to

Related issue - #364989 (closed)

What does this MR do and why?

Migrate the form_errors in app/views/admin/identities/_form.html.haml to Pajamas::AlertComponent. See &5550 (closed) for more details.

Screenshots or screen recordings

before	after

How to set up and validate locally

1. Visit http://GDK_INSTANCE/admin/users/root/identities
2. Enter the following input (5-6 times) to encounter an error:

"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>"><img src=x onerror=prompt(1)<script>alert(1)</script>

1. Notice the error alert

MR acceptance checklist

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Related to #364989 (closed)