When provided, this setting appends tpa_hint=<value> to the `next` URL provided for /login and /register page URLs, which bypasses the Open edX Login/Register page with an an automatic redirection to the TPA login/register URL.

This allows the already implemented tpa_hint feature to be automatically added to login, registration, and enrolment URLs generated throughout the platform.

Avoids auto-appending the tpa_hint parameter when the request is already in the TPA pipeline, to prevent infinite redirect loops, and adds tests to verify this behaviour.

LEARNER-966

LEARNER-2172

In particular, implement a validation API for registration,
where a client makes AJAX calls to the endpoints requesting
validation decisions on each input. Responses are strings
dependent on the type of validation error; if no error,
then empty string to indicate OK.

We have recently discovered that for any SSO Provider configured to skip
the registration form, we were auto checking the terms of service box,
which is a legal faux pas. Since IBM is planning to launch imminently and
is depending on this feature, we need to remedy this situation for enterprises
whose SSO Provider is configured to skip registration.

This PR hides all of the registration fields except TOS for this scenario
and disables the autoSubmit functionality that typically happens when skipping
registration.

When a user comes in through an sso provider and arrives at the login
or registration page, there is a warning message that comes up to indicate
that the user has to take an action to sign in and register and thus
link their sso account to their edx account. However, it is confusing,
particularly for the enterpise context. This diff disables these messages
from being rendered if these pages are being shown in an enterprise context.

Defaults to SUPPORT_SITE_LINK intentionally.
Also fixed surrounding quality tests, and overall
quality improvements.

Add Enterprise sidebar to login and registration views; remove unneeded fields; make registration form more narrow

Closes ENT-361.

LEANER-616

This change brings the Credentials API calls in line with those of other services. The change also makes it easier for the future switch to an asymmetric signing key.

LEARNER-629

LEARNER-616

LEARNER-605

LEARNER-381

[LEARNER-243]

LEARNER-394

ECOM-6463

ECOM-7195

The (now deprecated) programs service had several fields to set up configuration of the API.  We are removing the property/field references in codeas the first part of deprecating the model fields.  Also being removed are the model properties.

This reverts commit bc418c47.

ECOM-6463

We should not be using custom signing keys for each service at this time. We may want to return to this strategy in the future; but, this is not the direction any of our other services are going in.

ECOM-6541

nit: css

Move oauth_dispatch from lms to openedx/core.

This reverts commit 4dc744b1.

ECOM-4641