Add Hashtags detection Behavior

[rdelrosario]

Summary

A time ago I did this post about adding hashtag detection to any text in Xamarin Forms

API Changes

• Add this behavior
• Update Sample project

Intended Use Case

<Label FormattedText="{Binding Text}" >
        <Label.Behaviors>
                <behaviors:HashtagTappedBehavior Command="{Binding HashtagCommand}" HashtagColor="Green" />
         </Label.Behaviors>
 </Label>

Result:

[jfversluis]

Looks useful! Let's do it!

[AndreiMisiukevich]

I like it)

[sthewissen]

This seems very handy! :)

[Cfun1]

@jfversluis it seems it is blocked, not in progress anymore #172 (comment), also it is not properly linked to PR #172