Prompt the user when the invited MatrixId is not recognized

[giomfo]

Steps to reproduce

Scenario 1:

• Start a new DM by filling a non-existent MatrixId

Scenario 2:

• Open an existing group chat
• Invite a new member by filling a non-existent MatrixId

Outcome

What did you expect?

When the MXID is not recognised (= the getProfile failed (for example: M_NOT_FOUND error, or 502 code)) we should present a pop-up similar to the web client:

What happened instead?

• Scenario 1 : No warning is displayed

-> When some provided MXIDs are not recognised we should display the following alert:

title: "Confirmation"
message: "Unable to find profiles for the Matrix IDs listed below. Would you like to start a DM anyway?" + list of mxId(s)
actions: "Cancel" / "Start DM anyway"

• Scenario 2: No warning is displayed

-> When some provided MXIDs are not recognised we should display the following alert:

title: "Confirmation"
message: "Unable to find profiles for the Matrix IDs listed below. Would you like to invite them anyway?" + list of mxId(s)
actions: "Cancel" / "Invite anyway"

Your phone model

No response

Operating system version

No response

Application version and app store

No response

Homeserver

No response

Will you send logs?

No

Are you willing to provide a PR?

Yes