Add HTML validation and remove jQuery validation from registration form

[rebecca-shoptaw]

Dependency to epic #7694. Sub-task of #9205.

Describe the problem that you'd like solved

While the new real-time validation for formatting errors added in #2055 shows very helpful errors to the user, it does not actually prevent users from submitting forms with badly formatted inputs.

Proposal & Constraints

While in most cases, this problem could be solved speedily by adding relevant HTML attributes to the inputs, this particular form is generated via the forms library in form.py:
In the HTML:

openlibrary/openlibrary/templates/account/create.html

Lines 53 to 61 in ca46cbf

	<form class="olform create validate" name="signup" method="post" data-i18n="$json_encode(i18n_strings)" action="">
	$if form.note:
	<div class="note">$form.note</div>
	$def screenname_url(): $_('Your URL'): https://openlibrary.org/people/<span id="userUrl">$(form.username.value or _('screenname'))</span>
	$:field(form.email)
	$:field(form.username, suffix=str(screenname_url()))
	$:field(form.password)

In the Python:

openlibrary/openlibrary/plugins/upstream/forms.py

Lines 74 to 82 in ca46cbf

	class RegisterForm(Form):
	INPUTS = [
	Textbox(
	'email',
	description=_('Your email address'),
	klass='required',
	id='emailAddr',
	validators=[
	vemail,

):

However, luckily it is fairly straightforward to add any desired HTML attributes to the attribute list above, which translate to the correct attributes in the final rendered HTML.

One other issue here, which we also encountered in #8871, is that the jQuery validate plugin, called via the validate class in the form, starts adding extra error messages to the email field on key-up.

Since the validate class has no other effect on the form, as validation is handled by init_realtime_validation and forms.py validators, I propose removing it.

Additional context

• Form library: utils/form.py
• Registration form set-up: plugins/upstream/forms.py
• Registration form HTML: templates/account/create.html

Stakeholders

@cdrini