Follow-up: Move definition of library default columns out of header file

[uklotzde]

Follow-up of #3328. The definition of this constant does not belong in a header file.

Be careful when merging to main! The COVERART_DIGEST column probably needs to be added manually.

[Holzhaus]

I would be extremely convenient if the order of elements in the stringlist would also affect the default column order. It's quite complicated to grasp where the order comes from.

[uklotzde]

I would be extremely convenient if the order of elements in the stringlist would also affect the default column order. It's quite complicated to grasp where the order comes from.

I agree. But this PR is just a technical clean up.

Figuring out how to entirely replace the table views in QML instead of rewriting this legacy code might be a more sustainable investment of work and effort.

[uklotzde]

Ping.

[ywwg]

Can you add a comment defining what is meant by "default columns"? Or maybe, it should be renamed to like "LIBRARY_VIEWABLE_COLUMNS". otherwise LGTM

[uklotzde]

@ywwg I have only moved your code from a .h file into a .cpp file for technical reasons. I will not improve the code.

[Be-ing]

@ywwg if you want to make further improvements please open another PR. But keep in mind that asking others to expand the scope of PRs can be frustrating and slows down development.