Based on latest design feedback, update UI to make
it simpler for users.

Relates:
https://gitlab.gnome.org/GNOME/gnome-online-accounts/-/issues/317

Making up our own custom names for different account types is causing
additional confusion, not reducing it. Fixes #305

Remove an errant period, per the HIG.

Microsoft has a website up to aid translators with terminology in
their products, so add the link wherever "Tenant" occurs.

See https://learn.microsoft.com/globalization/reference/microsoft-terminology

GNOME 46 Freeze Breaking Backport

See merge request GNOME/gnome-online-accounts!206

In some cases OAuth properties may be `NULL`, which results in
dumping `NULL` into a `GVariant` and storing invalid data.

Always use the class-defined getters when OAuth properties are
used, since they handle the fallbacks.

closes #325

These strings are visible to the user to provide error information.
Apart from these two strings, most were already marked as translatable.

Instead of trying to read the user identity from `/v1.0/me/drive`, get
it from `/v1.0/me` where it is guaranteed to be the signed in user.

See: https://learn.microsoft.com/en-us/graph/api/user-get?view=graph-rest-1.0&tabs=http#example-2-signed-in-user-request

closes #327

When parsing the response, check for "mail" rather than "email"
before falling back to "displayName".

Use more caution with value types and print better debug
information.

Fastmail (now) has an app password scope that covers all DAV
services (WebDAV/CalDAV/CardDAV), so expect newly setup accounts
to use this password and auto-configure all endpoints.

Fix a quirk in the account setup dialog that allowed a sign in attempt
with an empty username/password.

Currently `dav.mailbox.org/.well-known/{caldav,carddav}` redirect to
`https://dav.mailbox.org/` instead of the correct path.

Update the URIs to autoconfigure mailbox.org to workaround this.

When Fastmail accounts are autoconfigured, the URIs are set to the
endpoint recommended in the documentation. Re-authenticating these
URIs would require the `check()` function to automagically fallback
to well-known path redirects.

Since the TXT record for fastmail.com doesn't contain a path,
amend the URIs to use the same well-known path that would be discoverd.

Some services like Fastmail and mailbox.org support content-restricted
app passwords, similar to OAuth scopes. Additionally, some providers
advertise support for features that are not available for some
account types.

Defer authentication errors until discovery is exhausted, to account
for expected authentication errors for these situations.

Assuming any DAV endpoint supports file access leads to many false
positives, and complicates discovery.

Until GoaDavClient emulates Gvfs' PROPFIND behaviour, only accept
endpoints without CalDAV/CardDAV support as being for file access.

It's reasonable to assume that URIs are being discovered in order of
preference (i.e. TLS), so stop overriding existing endpoints.

Some services have content-restricted app passwords, which make
(attempted) authentication a required step even when auto configuring
endpoints.

Move the short-path earlier when possible, so that endpoints can be
individually authenticated.

Avoid assigning all the features of a given message to the config,
to prevent pre-empting file access detection.

Backports for GNOME 46

See merge request GNOME/gnome-online-accounts!231

Ensure the provider dialog is closed, when bound to a cancellable task
that is cancelled.

Refactor to compose the steps of binding a task to a window and
presenting the window into a single method.

Providers now call `goa_provider_task_run_in_dialog()` to present the
window and release control to user interaction.

Use the `icon-dropshadow` CSS class on the account overview page.

closes #337

Backports for GNOME 46

See merge request GNOME/gnome-online-accounts!238