Missing `height` attribute on custom emotes

[bitfl0wer]

Describe the bug

MSC2545 is quite clear about the fact that the height attribute MUST be specified when sending custom emotes.

Sable does not currently do this, which causes visual issues with clients not supporting custom emotes.

Reproduction

No response

Expected behavior

The height attribute must be present in sent custom emotes. Ideally, it is set to 32px, as the MSC recommends.

Platform and versions

Sable version: v1.15.2 (1c46081)

Additional context

No response