fix: add a way to take a heap snapshot (patch for release49)

[nytamin]

About the Contributor

This pull request is posted on behalf of the NRK.

Type of Contribution

This is a hack, to allow for memory leak troubleshooting.

New Behavior

This PR adds a GET method that returns a NodeJs heap snapshot, which can be inspected in the Chrome devtools.

Testing Instructions

1. Go to Settings / Core System Settings
2. At the bottom of the page, you find a new button under Memory troublshooting

Time Frame

This is urgent for us, please review and merge it as soon as possible.

Other Information

Status

• [x] PR is ready to be reviewed.
• [x] The functionality has been tested by the author.
• [ ] Relevant unit tests has been added / updated.
• [ ] Relevant documentation (code comments, system documentation) has been added / updated.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 67 lines in your changes are missing coverage. Please review.

Project coverage is 59.02%. Comparing base (a04c695) to head (2138abd). Report is 19 commits behind head on release49.

Files	Patch %	Lines
meteor/server/api/heapSnapshot.ts	0.00%	66 Missing :warning:
meteor/server/main.ts	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## release49 #1165 +/- ## ============================================= - Coverage 59.07% 59.02% -0.06% ============================================= Files 473 474 +1 Lines 71613 71697 +84 Branches 3724 3728 +4 ============================================= + Hits 42308 42320 +12 - Misses 29258 29332 +74 + Partials 47 45 -2 ```

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