Address issue importing Blacklight module in masonry and slideshow javascript

[mamrey]

The import statement in the masonry and slideshow javascript modules fail to resolve.

Both files import the Blacklight module from 'blacklight-frontend' instead of 'blacklight'. This change to unify the Blacklight import became available on blacklight 9.X, and there is a draft PR to backport it to Blacklight 8.X, and specifically mentions spotlight.

Furthermore, the application.js entrypoint uses the blacklight 8.X import statement, i.e. `import Blacklight from 'blacklight'.

I suspect this may also be related to the issues with esbuild.

Even if we merge in the backport PR on blacklight 8, the import will still be broken for all previous versions of blacklight that the v4.X of this gem supports. Creating some sort of conditional way to import the module depending on blacklight version sounds overly complex. I think the best bet here is to align the Blacklight import in the masonry and slideshow js files to the Blacklight import generated in the application.js entrypoint

[mamrey]

Additional context:

In blacklight 8, when building the internal test app with the j esbuild flag, the rails application does not use importmap. Blacklight selects the Propshaft asset generator which injects import Blacklight from 'blacklight-frontend' into the application.js entry point of the host application. This makes sense because without ImportMap, we are assuming we're pulling in blacklight javascript through the npm package, which is called blacklight-frontend.

The blacklight 9 PR mentioned above, and the intended blacklight 8.X backport, unify the names when importing blacklight javascript from the gem files when using importmaps, and from the npm package when using some node-based bundler.

This suggests that these imports work when using a node-based bundler, but do not work with importmap.

[mamrey]

closed with #210