Reset ui-text-input automatically when Mode is "password"

### Description

ui-text-input can be set to "password", which is a good feature. Propose to reset the input after sending out the message in this mode.

### Have you provided an initial effort estimate for this issue?

I am no FlowFuse team member

Inspect the ui-text-input implementation and the path that sends its message. Confirm how the password mode is identified and verify that the input resets after sending in that mode while other modes retain their value.

Written by the indexing model from the issue text.