Search in the contacts for the field "Matrix"

### Your use case

#### What would you like to do?
When you get a contact from someone and it contains a Matrix field, it would nice if element would find it.

#### Why would you like to do it?
I am not a big fan of leaking non app relevant data to the app.

But if there is a Matrix field in the contact, Element should be able to read it.

#### How would you like to achieve it?
Search in the contacts for the field Matrix which can contain plain MX-ID, matrix.to link and matrix: link.

### Have you considered any alternatives?

_No response_

### Additional context

Would be great if i could tell Element only to search for this field because I don't want to leak any other data!

Start by locating Element's contact-search entry point and the handling of contact fields; the issue specifies Matrix fields containing a plain MX-ID, matrix.to link, or matrix: link. Done means Matrix values can be searched, with an option to search only that field so unrelated contact data is not exposed.

Written by the indexing model from the issue text.