Initial file reference tag support - group logos

Initial implementation of the file reference tag support as per the draft spec:
file references can have one or more string tags, and clients can use this to
filter to known tags.

Notes:
- The spec may still separate tags in the filename by '_' or '.', we can fix that
  later.
- I simplified ContestSource.getFile() here because of code overlap although it's
  not directly related - source just needs to know the type and id, not the
  entire object.
- I got rid of ContestObject.ReferenceMatcher/ImageSizeFit and made
  getBestFileReference() private. My original thought years ago was that we could
  expose multiple ways of picking the 'best' file, but we never used/needed it.
- I updated ContestObject.getFile() to match getRefImage(), and added an optional
  tag.
- Team, person photo just pass null for the tag - I don't think we'll ever need
  light/dark for photos.
- I updated group logo and the one use in TeamAwardPresentation to show the API
  and client change for tags. I expect to do the same thing for logos and banner
  in info (contest) and organization, but this PR is already big enough so that
  will come next.

First part of #1228.

Remove getFiles() pattern

I'm not sure when this pattern was added (when file references were added and could
include multiple files?), but ContestObject.getFiles() is used by a bunch of file
reference properties, none of which are then used.

I don't think it's a good pattern to force all file references of a property to
be downloaded at once. (the playback contest does this, but with targeted
comparisons) It is not consistent or done with any other file references and
just complicates the API, so removing this.

Remove disk scanning logging

When I added periodic disk scanning for contests I added tracing so that I could confirm
it was happening and see how long it was taking each time, especially on large contests.
I've never seen more than 10-20ms in dev or prod and the constant tracing even when
'nothing is happening' is annoying and adds up if you leave the contest running, so I'm
removing it.

Allow CORS for HLS

No need to drop untrusted listeners if we're not listening

Found a case where the video aggregator is getting loaded even if video is not
configured. This just avoids calling getInstance() and triggering the load.

QR code generator util

Added a main() method to the QR code generator to make it easy to generate codes.
Just run it with two arguments: the QR code to generate and the filename to use.
An image with that QR code will be generated with that name in the working folder.

Also documented a few handy codes for our current scanners.

First Solution presentation should load from /present

Updates the First Solution presentation:
- Moved configuration from data/firstsolutions.txt embedded in the jar to look for
  /present/first-solution/solutions.txt instead.
- When there is no file or no data, a message is shown to point the user in the
  right direction. Documentation is still an issue, but this is a start.
- Added support to ImageHelper to rescale and support SVGs, and added it to this
  presentation as well as the CCS, ImageBuild (logo), and Promo presentations.
- Changed 'Year' column to 'Contest' to be a little less specific and allow wider
  use (e.g. could use 'WF48' or other strings. Updated translation files to match.

Sample data was pushed to the wf49baku repo in case we copy that repo or need a
reference next WF.

Resolver message presentation

Allows 'after awards' to be simple messages using the message presentation.

Improve button and message for clearing cache

Add option to showScoreboard before 'after award'

Shows the scoreboard between the award and the chained / after award.