[proposal] Make headers call for AgentRestClient dynamic

[cre8]

What issue is this PR fixing

Fixes #1313

What is being changed

The AgentRestClient constructor is able to handle functions calls for the headers. This allows to pass dynamic values like an access token that needs to be updated frequently.

Quality

Check all that apply:

• I want these changes to be integrated
• I successfully ran pnpm i, pnpm build, pnpm test, pnpm test:browser locally.

 FAIL  packages/data-store/src/__tests__/data-store-orm.test.ts (25.45 s)

                                                                                                                                           
  ● Test suite failed to run                                                                                                               
                                                                                                                                           
    EBUSY: resource busy or locked, unlink './tmp/test-db2.sqlite'                                                                         
                                                                                                                                           
      143 |   afterAll(async () => {                                                                                                       
      144 |     ;(await dbConnection).close()                                                                                              
    > 145 |     fs.unlinkSync(databaseFile)                                                                                                
          |        ^                                                                                                                       
      146 |   })                                                                                                                           
      147 |                                                                                                                                
      148 |   test('search presentations by verifier', async () => {                                                                       
                                                                                                                                           
      at Object.<anonymous> (packages/data-store/src/__tests__/data-store-orm.test.ts:145:8)  

This error has nothing to do with the changes, but resulted in a incomplete test run (OS: Windows 11)

• I allow my PR to be updated by the reviewers (to speed up the review process).
• I added unit tests.
• I added integration tests.
• I did not add automated tests because the package has no test implemented, and I am aware that a PR without tests will likely get rejected.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (ac1b620) 85.47% compared to head (3b43ea3) 85.47%.

Additional details and impacted files

@@           Coverage Diff           @@
##             next    #1314   +/-   ##
=======================================
  Coverage   85.47%   85.47%           
=======================================
  Files         170      170           
  Lines       18950    18952    +2     
  Branches     2115     2116    +1     
=======================================
+ Hits        16197    16199    +2     
  Misses       2753     2753           

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[mirceanis]

Thanks for posting this and for leading with an issue explaining the changes!

Just one nit to fix, otherwise looks great!