[Feature Request] Allow User Mentions When Submitting Comments

[vkhitrin]

Is your feature request related to a problem? Please describe.
When submitting comments on work items, in the web UI it is possible to mention users using @<NAME> syntax.

At the moment, when submitting a comment, the comment should be parsed as ADF to support mentions and
other capabilities.

Describe the solution you'd like
Attempt to parse the provided comment markdown into ADF.

Describe alternatives you've considered

Additional context
Various Jira instances will have various capabilities when formatting with ADF, but user mentions via ADF should be a
common scenario shared across all instances.

[whyisdifficult]

@vkhitrin this is a nice feature to have but one that it's tricky to implement. See my comment to another similar request: #126 (comment)

[vkhitrin]

Thanks @whyisdifficult, it has been a long time since I have last interacted with the self-hosted versions of Jira/Atlassian, and I forgot that they may not use ADF.

I guess the only option will be to have a separate formatter/parser for the different Jira versions if it is decided to proceed with features like this.

Also, if continuing to support ADF, there has to be some process to keep track of the schema when it changes (https://www.npmjs.com/package/@atlaskit/adf-schema).