feat: use packagr to build as angular package format

[terencehonles]

This PR attempts to convert this repo to use ng-packagr to produce builds according to the Angular package format which is needed for AoT builds, and will probably be required as we progress from Angular 7 to beyond.

I tried to leave most things as they were, but the changes I made were the following:

• Fix imports to be relative within a package, and absolute across packages
• Simplify how the package.json is templated (only the package.json keys defined in scripts/update-package-json.js are copied from the root into the subpackage package.json)

This does seem to work for us, but there are a couple things that have not been tested or are things to point out:

• ng-packagr does not load in peer libraries, so in order to allow the build process to be automated I install copy the core library to node_modules after building it and then build the peer libraries. I believe this is related to the issue Feature: dependencies between npm packages ng-packagr/ng-packagr#1174 and there is not a more elegant solution to this. (If there is then that should be done)
• because of the above point I'm not sure how easy the development flow is, but building from scratch does not seem to take too long.
• I only tested this when building the package with the Angular compiler. I do not know if the the other bundles are working, and running some tests would help :)

[codecov]

Codecov Report

Merging #1634 into master will decrease coverage by 0.03%.
The diff coverage is 7.14%.

@@            Coverage Diff             @@
##           master    #1634      +/-   ##
==========================================
- Coverage      40%   39.96%   -0.04%     
==========================================
  Files          41       41              
  Lines        1800     1799       -1     
  Branches      147      154       +7     
==========================================
- Hits          720      719       -1     
  Misses       1079     1079              
  Partials        1        1

Impacted Files	Coverage Δ
packages/core/core.module.ts	0% <0%> (ø)	⬆️
packages/core/directives/fit-bounds.ts	0% <0%> (ø)	⬆️
...nazzy-info-window/directives/snazzy-info-window.ts	0% <0%> (ø)	⬆️
...ker-clusterer/services/managers/cluster-manager.ts	54.41% <100%> (-0.67%)	⬇️

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[ghost]

hey @terencehonles . Thanks for sending the PR. Can you please merge the changes from master into your branch? Make sure it's FF only so there are no merge commits.

Thanks in advance!

[terencehonles]

@doom777 @SebastianM this PR should be updated, but as I noted in the description I only did limited testing in an Angular 7/8 app.

[ghost]

Good change, and works in my case. However this PR cannot be merge without its follow up, since it takes a bunch of things back like versioning

[terencehonles]

I updated the code to match master. I haven't had a chance to test it, but it does build w/o any warnings.

[terencehonles]

I updated some more of the dev dependencies and cleaned up some of the tools I made unnecessary and fixed a test that broke when upgrading versions (I had also fixed it on #1648 ).

I still haven't tested it aside from ensuring it builds, but it should be up to date now.

[terencehonles]

It does seem the changes still build against the application we have, but I don't have the right data locally to run it so I'll have to test running the actual application elsewhere later.

To test you can use the release or more specifically ngmaps.core-2.tgz (The other was built when I initially drafted this PR)

[terencehonles]

The changes do still seem to work as before. I don't use any package other than @agm/core and I only use angular w/ aot so if anyone has a different workflow or uses the other packages they should test those.

[terencehonles]

Let's not let this get stale again. It wasn't my fault this wasn't merged in earlier. There was some clean up I was able to add because there was more time, but this PR is basically the same as it was in May aside from resolving merge conflicts.

We need to get this into mainline so changes are made with respect to this change rather than me trying to resolve what happened in the meanwhile.

If there is concern about the other builds, we need to add some tests or easy way of verifying they are built correctly. The existing bundle formats that have been moved/updated should be prioritized, and new formats should be fixed as they are noticed to be broken (if they even are)

Just my 2¢

[ghost]

let's give @SebastianM a few days to review it.