Fix #2786 (links in HTML files in sub directories)

[codingphil]

↪️ Pull Request

Fixes bug #2786

See description of the bug above.

Now in Asset.replaceBundleNames() for each bundle of which the URL is inserted into asset content the a URL relative to its parent bundle is calculated so the URL is correct when the bundled output is deployed. This is only done when a relative public URL is specified in the options.

🚨 Test instructions

See added integration tests in packages/core/integration-tests/test/html.js

✔️ PR Todo

• Added/updated unit tests for this change
• Filled out test instructions (In case there aren't any unit tests)
• Included links to related issues/PRs

[mischnic]

Not sure if this is correct, but tests are failing on Windows (likely \ instead of /) - maybe you need to use the functions at path.posix.* instead of path.*.

[codingphil]

Not sure if this is correct, but tests are failing on Windows (likely \ instead of /) - maybe you need to use the functions at path.posix.* instead of path.*.

The path stored in the bundle object is always OS dependent which is OK in my opinion.
However, the link in the asset (HTML file) should always use unix-style directory separators in the URLs. With the first commit f73912d only for relative paths the directory separator was converted to unix-style but not for the absolute paths. The behavior for the absolute paths did not change.
With the commit 3c9f776 the URLs now always use unix-style directory separators in URLs.

[codingphil]

Now the test "elm should produce a basic Elm bundle" is failing and I'm not sure about the cause.
It says "The binary data at /home/vsts/.elm/0.19.0/package/elm/browser/1.0.0/objs.dat is corrupt."
https://dev.azure.com/devongovett/devongovett/_build/results?buildId=1352&view=ms.vss-test-web.build-test-results-tab

Other tests are just failing with exit code 1.

[mischnic]

You can ignore the elm test