No SAML login support, breaks Enterprise SSO options

### Your use case

#### What would you like to do
The homeserver provider I use has SAML login enabled, and only SAML login enabled. This is a requisite, and is present in standard Element client but *NOT* in Element X

#### Why would you like to do it?
Required for Enterprise SSO login on some homeservers including the ones I use

#### How would you like to achieve it?
Create/design a SAML login component to the mechanisms to login to Matrix homeservers, etc. in order to allow Element X to be used with SSO-enforced endpoints, which is CURRENTLY not an option.

### Have you considered any alternatives?

The only alternative is standard Element client or other Matrix clients.

### Additional context

_No response_

### Are you willing to provide a PR?

No

Start by reviewing Element X’s existing login flow and comparing it with the standard Element client’s SAML path; the issue names no files or tests. Define the supported SAML login behavior and integration points before implementation, then verify that an SSO-enforced, SAML-only homeserver can be used.

Written by the indexing model from the issue text.