add marshal/unmarshal for orderedmap without changing order

[tarunKoyalwar]

Proposed Changes

• we use orderedmap in nuclei to make sure order of headers/params do not change
• this pr implements custom json marshal / unmarshal interface to OrderedMap[k comparable,v any] type such that underlying output json remains the same
• used in Fuzzing layer enhancements + input-types support nuclei#4477