Allow replacing/updating parts of a http header value
Today you can only remove, add or completly re-write an http header value.
It should be possible to replace part of it.
For this to be useful, there should be a various of environment variables" which you should be able to reference.
There could include values currently being used by the frontend, backend and rule which is currently executing, as well as generic things like a UniqueID for the request, the date and time, browser type, country of remote client and so on.
Also you should be able to use complex regex for this, with multiple capture groups which should be able to use as replacement values.
It should also be possible to use a regex to capture a value from one http header value and use that capture to set/update/replace another header value.