Merge branch 'add-multi-get-header-policy' into 'main'

Add get multi header policy.

See merge request gaia-x/data-infrastructure-federation-services/tsa/policies!3

example/getHeader/1.0/policy.rego

@@ -2,4 +2,4 @@ package example.getHeader
 
 # gets the value for "x-cache-key" header and return it in the result
 # result is empty if the "x-cache-key" header is not sent in the request
-key = input.header["X-Cache-Key"]
+key = input.headers["X-Cache-Key"]

example/getMultiHeaders/1.0/policy.rego

+package example.getMultiHeaders
+
+key = input.headers["X-Cache-Key"]
+host = input.headers["Host"]
+