Split non-standard HTTP headers to non-standard and deprecated

[stephanie0x00]

Describe the bug
All non-standard and deprecated HTTP headers are currently gathered into 1 finding (#3127). Ideally these should be split into two categories.

As discussed with @noamblitz the title of the finding is renamed to "KAT-NONSTANDARD-HEADERS" for all these headers to include the headers listed below. In the future it would be nice to have these split into two categories: Non-standard findings and deprecated findings.

Seeing that these headers are not longer required, they are however still not-standard. Maybe we should introduce a finding for those (if don't already have one) and raise that for all of these non-standard headers. The following not standard headers would warrant this I'd think:

* [X-Forwarded-For](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-For)

* [X-Forwarded-Host](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-Host)

* [X-Forwarded-Proto](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-Proto)

* [X-DNS-Prefetch-Control](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-DNS-Prefetch-Control)

* [X-Robots-Tag](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Robots-Tag)

There's also the deprecated headers that might warrant a similar warning

* [Pragma](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Pragma)

* [Warning](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Warning)

Originally posted by @stephanie0x00 in #3127 (comment)