feat: add VM.get/setLabels() methods

[jpatokal]

feat: add VM.get/setLabels() methods

Implemented using VM.get/setTags() as a template.

Fixes #116

[codecov]

Codecov Report

Merging #515 into master will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #515   +/-   ##
=======================================
  Coverage   99.61%   99.61%           
=======================================
  Files          22       22           
  Lines       11861    11949   +88     
=======================================
+ Hits        11815    11903   +88     
  Misses         46       46           

Impacted Files	Coverage Δ
src/vm.js	99.60% <100.00%> (+0.03%)	⬆️

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[stephenplusplus]

Thank you very much! The only thing we need to merge is a system test to confirm it works when run against the real backend. Would you be willing to add those to "system-test/compute.js"? You'd have to test against your own project, then you can run them with npm run system-test from the root directory.

Specifically, you would probably add a new "describe" block to the file, and add something like:

// using "describe.only" will only run these new tests when you test with `npm run system-test`
// (you don't want to create a bunch of extra resources that the rest of our test blocks do)

describe.only('labels', () => {
  it('should get labels', async () => {
    const [labels] = await vm.getLabels();
    assert(labels.length > 0);
  });

  it('should set labels', async () => {
    const [operation] = await vm.setLabels({myLabel: true});
    await operation.promise();
    const [labels] = await vm.getLabels();
    assert.strictEqual(labels.myLabel, true);
  });
});

No worries if not, just let me know!

Thanks again for helping out 👍🏻

[stephenplusplus]

Perfect! Just need system tests before we can merge.

[jpatokal]

System tests added. Instead of adding a new describe block, I placed it in the existing vm block, so we don't need to spin up a new VM just for this.

Note that the setLabels method requires explicitly passing in the label fingerprint. IMHO this is a little unintuitive, but it parallels the underlying API and the existing setTags method as well.

[stephenplusplus]

Looks perfect, thank you!