Minor improvements to API v2

[Ninjaclasher]

• Sort all list endpoints by ID, which reduces the likelihood of objects moving between pages during requests. Objects will only shift if an object is deleted, which usually does not happen.
• Add a list filter for ID (and other identifier fields), so users can request a list of only the objects they care about (rather than requesting all and then filtering on their side)
• Use the rating from Profile.rating instead of re-computing it each time. This attribute should already be updated during each contest rate.

[codecov-commenter]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (292ba1a) 46.83% compared to head (985fe9a) 46.84%.

Files	Patch %	Lines
judge/views/api/api_v2.py	66.66%	1 Missing :warning:

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #2296 +/- ## ========================================== + Coverage 46.83% 46.84% +0.01% ========================================== Files 250 250 Lines 13275 13275 ========================================== + Hits 6217 6219 +2 + Misses 7058 7056 -2 ```

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[Ninjaclasher]

Docs PR: DMOJ/docs#154