This will help fix COUNT request results

For consistency

All request that could return more than one row (ie. all member function
that used to return an std::vector<std::shared_ptr<T>> will now return a std::unique_ptr<Query<T>>
The query object can return:
- The amount of row represented by that query (->count())
- A subset of the rows (->items(count, offset))
- All rows (->all())

As opposed to the previous strategy, which was requiring every artist to
have at least an album

This doesn't contain the migration code as there is more changes to come
into the Artist table, and those change would basically roll back most
of this commit associated migration code

sqlite doesn't warrant a `true` boolean will have a value of 1, but
`false` will always be 0

This is a fixup for commits:
- d71d36bd
- 1a0d7284
- 41f045b9

Signed-off-by: Hugo Beauzée-Luyssen <hugo@beauzee.fr>

And use SQL to concanate string, as the compiled request will be cached.