Add Change getter graphQL api

[rohithbalaji123]

Part of #612

New Behavior

Description

Add changes graphQL API to fetch all the changes available to be displayed in admin panel. This is different from changeLog in the sense that, changeLog also fetches lastViewedAt timestamp which is not related to admin panel functionalities. The newly added API internally reuses the same repository methods used for changeLog. This also adds the permission check whether the user can view the changes.

[codecov]

Codecov Report

Merging #905 into master will decrease coverage by 0.13%.
The diff coverage is 31.81%.

@@            Coverage Diff             @@
##           master     #905      +/-   ##
==========================================
- Coverage   52.40%   52.26%   -0.14%     
==========================================
  Files         133      133              
  Lines        3227     3249      +22     
  Branches      157      157              
==========================================
+ Hits         1691     1698       +7     
- Misses       1468     1482      +14     
- Partials       68       69       +1     

Flag	Coverage Δ
#golang	70.47% <31.81%> (-0.44%)	⬇️
#typescript	23.65% <ø> (ø)

Impacted Files	Coverage Δ
backend/app/adapter/gqlapi/resolver/authquery.go	31.11% <0.00%> (-10.07%)	⬇️
backend/app/usecase/authorizer/authorizer.go	33.33% <0.00%> (-6.67%)	⬇️
backend/app/usecase/changelog/changelog.go	82.50% <77.77%> (-0.60%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update c05f3c7...83c39f8. Read the comment docs.

[arberiii]

Hey @rohithbalaji123! Thank you for working on this! Left a few small comments.

[magicoder10]

@rohithbalaji123 GraphQL client side query can decide which fields to fetch and ignore those that are not needed.

[rohithbalaji123]

The reason why I went for a new API is that they are being used for completely different purposes and their fetching mechanism might change in future.
For instance, when we start implementing #595 , that will be specific to user side changelogs, while admin will still need to get all the changes.