Allow extensions to contribute to issue body when using Issue Reporter

[karrtikr]

When an extension, say Python, is selected in the report issue dropdown:

"Steps to reproduce" should be auto-filled with extension specific templates if available.

Right now the workaround is that every extension has its own report issue command, which isn't always used when reporting issues (users rely on the general Help: Report Issue instead):

[TylerLeonhardt]

related: #46726

[karrtikr]

An easy solution for this would be to provide a hook when an extension is selected in the dropdown, which then launches the extension specific report command. This can be specified in 'package.json'.

[bwateratmsft]

For Docker and several Azure extensions, we'd like to use the built-in issue reporter but also attach some additional data (error details, call stack, etc.), while still requiring users to fill something into the repro steps field.

[TylerLeonhardt]

/duplicate #46726