NEW Convert frontend assets to use silverstripe/webpack-config

[robbieaverill]

Resolves #79

Also resolves #67

[robbieaverill]

@sachajudd I've added the changes to this pull request to show the last updated date on the report, for example:

I wasn't able to make the text green after updating the report because the reloading of the GridField is done with AJAX and we'd need to wait for that to complete before setting the text colour to green. The (legacy) GridField javascript API in core does have a "success callback" for GridField's reload() function, but it gets executed before the GridField is reloaded so it's basically pointless.

I tried to add it to the initial report generation based on whether the report is rendered via AJAX, but clicking on the "Check for updates" also refreshes the report via AJAX when you first click on it (not ideal, but it is what it is for now).

Are you happy to leave out the green colour and shorter text?

[sachajudd]

Right, thanks for explaining. One of the AC's was to be able to attract the users attention so probably have to chat with @clarkepaul if we want to still achieve this.

[sachajudd]

@robbieaverill P.C missed a couple of things. Could you please remove the commas and rearrange the time to be 31 May rather than May 31. Cheers.

Edit - defined by user's locale so 👍

[robbieaverill]

Sweet, checked with @clarkepaul and we've logged the necessary improvements for the green text at #87

[ScopeyNZ]

LGTM