Remove ng-high-memory & remove Node v10 support

[artlowel]

References

• Fixes Make memory to build UI more configurable #1037

Description

This removes ng-high-memory, because starting from node 12, it is no longer needed or even advisable to set the amount of memory required.

Instructions for Reviewers

To test this, verify that the scripts that used ng-high-memory still work: start, test, ci, and lint-fix

Checklist

• My PR is small in size (e.g. less than 1,000 lines of code, not including comments & specs/tests), or I have provided reasons as to why that's not possible.
• My PR passes TSLint validation using yarn run lint
• My PR doesn't introduce circular dependencies
• My PR includes TypeDoc comments for all new (or modified) public methods and classes. It also includes TypeDoc for large or complex private methods.
• My PR passes all specs/tests and includes new/updated specs or tests based on the Code Testing Guide.
• If my PR includes new, third-party dependencies (in package.json), I've made sure their licenses align with the DSpace BSD License based on the Licensing of Contributions documentation.

[tdonohue]

@artlowel : This looks great, however if you look at our Node v10 build in GItHub Actions, you'll see it's hitting memory issues now.

So, for the time being, I think we need to set NODE_OPTIONS="--max_old_space_size=8192" in our CI configuration. Doing so should just be a matter of adding this to the env section

env:
   # Tell node to use a max of 8GB memory
   # NOTE: this can be removed once we drop support for Node v10 as v12+ manages memory automatically
   NODE_OPTIONS: '--max_old_space_size=8192'

That should get the v10 builds/tests working again.

UPDATE: Just saw your note in #1037 that Node v10 is EOL as of April. So, the alternative here would be to switch us now to v12 & v14. That'd just be changing this line: https://github.com/DSpace/dspace-angular/blob/main/.github/workflows/build.yml#L22 (Though we also should update the README too obviously)

[tdonohue]

After a bit more thought, maybe we should just go with my alternative suggestion. Moving us off Node v10 now would simplify our documentation (as we'd need to warn them to set NODE_OPTIONS), and it seems like this may be a good opportunity to add in v14 to our CI tests. But, I'm open to suggestions

[artlowel]

I agree, I'll update the PR to switch to node 12 and 14 builds on Github Actions

[tdonohue]

👍 Thanks @artlowel . This looks correct and is passing tests for Node v12 & v14.