Add special rendering for deprecated operations

[pgolm]

This PR adds visual hints to deprecated operations which discussed in #286.

[RomanHotsiy]

Looks awesome! Thanks for kicking it off @pgolm. Sorry for long reply.

Just one thing. Could you instead of adding label Warning: Depratecated add deprecated class to operation header just same way as you did here https://github.com/Rebilly/ReDoc/pull/290/files#diff-74068f897e8aeb7897a9b86c3d9cba68R3.
Then using this class and :after pseudo-selector add orange badge Deprecated to the end of the header. + maybe make header line-crossed too.
I think it will look better. What do you think?

[pgolm]

Thanks for your review. Sounds very good to me 👍. I will change it later these day.

[pgolm]

I've added the deprecated badge to the header. But the strikethrough header looks a little bit to heavy for me, so i left it. Any thoughts?

[SebastianStehle]

Btw: You can also use [class.deprecated]="options.deprecated"

[pgolm]

Thanks for the hint @SebastianStehle. I didn't know that. In the source i can't find any usage of it. Are there any best practice?

[RomanHotsiy]

@pgolm oh my... It's so huuuge 😂

I will merge this PR and then change the style of the badge myself if you don't mind

[pgolm]

@RomanGotsiy 🙈👍

[RomanHotsiy]

I believe it looks a bit better this way :)

Will release a new version till the end of the week.

[ssteeg-mdsol]

Thanks for adding this feature, will it be released soon?

[RomanHotsiy]

Yes, will cut a new release until the end of this week!