Added backend api functions for to change 'resolve' status in backend

[goelaine]

Fixes #3
Added two functions present in src/api/topics.js that change the 'resolved' field of the post in the database to true for markResolved and false for markUnresolved.
These functions should be called from the frontend when user manually presses button to toggle the 'resolved' status.
Functions are valid to be called on regardless of the current state of the 'resolved' field (ie. able to call 'markResolved' for a post whose 'resolved' field is already set to True).

Tested with printing to console, once frontend was implemented in pr #28

Wrote automated unit tests in pr #18 to increase coverage
Note: all lint and test do pass when the last commit was made! I just accidentally re-ran it (10/9/2024) and the coveralls failed to run at all because of a configuration problem, as this is a closed issue and completed build. See the successful test and coverage report here: https://github.com/CMU-313/nodebb-f24-team-kale/actions/runs/10984399635/attempts/2

[coveralls]

Pull Request Test Coverage Report for Build 10984399635

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 2 of 6 (33.33%) changed or added relevant lines in 1 file are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.01%) to 81.818%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/api/topics.js	2	6	33.33%

Files with Coverage Reduction	New Missed Lines	%
src/meta/errors.js	1	76.74%

Totals
Change from base Build 10983572388:	-0.01%
Covered Lines:	22345
Relevant Lines:	25869

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💛 - Coveralls

[goelaine]

Now covered with new test cases in pr #29