Use the "check changes" API to highlight the Run button again

[arildm]

There should probably only be one primary action, at any time, i.e. one button highlighted in blue. After an annotation has been successfully run, the primary action is to install it in Korp. But if I upload a new file, or if I change some annotation settings, the primary action should be to run the annotation again. For this, we can use the check changes API call.

[arildm]

It should also be evident that the export is outdated if there were config/source changes.

[arildm]

Another case that I think we can include in this issue: after annotation is done, even if there are no config/source changes, the "Run annotation" button is currently enabled. It should perhaps be disabled.