Add support for Slack-flavored markdown

[Klikini]

I added a new SlackFlavored config option:

var config = new ReverseMarkdown.Config {
    SlackFlavored = true
};

When enabled, ReverseMarkdown will:

• Use * instead of ** for bold
• Use _ instead of * for italic
• Use ~ instead of ~~ for strikethrough
• Use a bullet character (•) for lists because Slack does not parse lists using * or - when sending messages via the API
• Throw a SlackUnsupportedTagException when trying to convert the following tags because Slack doesn't support them in messages:
  • <hr>
  • <img>
  • <sup>
  • <table>, including <td> and <tr>

[mysticmind]

Thanks for the PR, will review tomorrow during my day. I have kick started the CI.

[mysticmind]

@Klikini Hey, sorry about the electronic silence, had to travel a bit due to personal work. I will review this PR this week and pull it in.

[mysticmind]

@Klikini The code changes look fine, I will pull it in and make few changes. Is it possible for you to add some unit tests for this functionality?

[Klikini]

Sure, I should have some time later this week to work on tests.

[Klikini]

Unit tests are done. I only ran them locally under .NET 8, but hopefully they work the same under .NET 6 and 7.

[mysticmind]

Thank you, will take a look at it in my morning and pull it in.

[winzig]

Is this going to be part of an official release @mysticmind

[mysticmind]

Sorry, have been out with a personal emergency. I will take look and release in the next few days.

[mysticmind]

@Klikini @winzig I have released v4.7.0 and available in NuGet, this functionality is available to use now.

[Klikini]

Thank you! I hope everything is okay.

[mysticmind]

Thank you! I hope everything is okay.

Hey @Klikini, thanks for the concern, getting better!