Add a button for "Format as code"

[johanneskastl]

Problem Description

Underneath the text area there are three buttons for "bold", "italic" and "Insert link". There is none for "format as code".

Proposed Solution

An additional button for "Format as code". Maybe configurable.

Additional context

I know I can type backticks to format as code, but it would be great to have this as a button, too.

[andersk]

Closing as duplicate of

• zulip/zulip#20302