feat: updating filter result to add decorations

[varkey98]

Description

Adding a Decoration field to FilterResult. The Decoration struct can have mutations defined on request or response objects which should be applied on a filter result match. Starting with request header injections, in which a list of headers can be specified to be injected on a filter evaluation match

Checklist:

• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• Any dependent changes have been merged and published in downstream modules

[varkey98]

I've updated the 2 server instrumentations we have on goagent as well to use the updated filter result, pls let me know if we want to separate it onto a different pr

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 59.89%. Comparing base (849c958) to head (cc405c4).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #236      +/-   ##
==========================================
+ Coverage   59.45%   59.89%   +0.44%     
==========================================
  Files          70       70              
  Lines        2348     2364      +16     
==========================================
+ Hits         1396     1416      +20     
+ Misses        867      863       -4     
  Partials       85       85              

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