fix(credential-ld): fix LDdefaultContexts file extensions

[andyv09]

What issue is this PR fixing

Fixes issue where some files without .json suffix cannot be imported and throw Can't resolve error.

What is being changed

Adds .json to filenames that are missing it in ld-default-contexts.ts

Quality

Check all that apply:

• I want these changes to be integrated
• I successfully ran yarn, yarn build, yarn test, yarn test:browser locally.
• 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 _________, and I am aware that a PR without tests will likely get rejected.

[codecov]

Codecov Report

Merging #1086 (4f7836e) into next (125bf42) will decrease coverage by 0.50%.
The diff coverage is 77.27%.

❗ Current head 4f7836e differs from pull request most recent head fa1640d. Consider uploading reports for the commit fa1640d to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             next    #1086      +/-   ##
==========================================
- Coverage   80.25%   79.74%   -0.51%     
==========================================
  Files         118      132      +14     
  Lines        4056     4739     +683     
  Branches      875     1016     +141     
==========================================
+ Hits         3255     3779     +524     
- Misses        798      960     +162     
+ Partials        3        0       -3     

[mirceanis]

Looks great