matrix.to permalink is not URL encoded

### Steps to reproduce

When mentioning a user using @, the client includes a matrix.to link in the formatted body of the event.

The Matrix specification explicitly requires matrix.to URLs to be URL-encoded as specified in https://spec.matrix.org/unstable/appendices/#matrixto-navigation
.
The current implementation does not apply URL encoding, resulting in non-compliant matrix.to links.

### Outcome

#### What did you expect?
`
"formatted_body": "User"
`
#### What happened instead?
`"formatted_body": "User"`

### Operating system

_No response_

### Browser information

_No response_

### URL for webapp

_No response_

### Application version

_No response_

### Homeserver

_No response_

### Will you send logs?

No