Fix updating brush tips or other resources

Before this commit, if the user created a new brush tip,
then opened it in Krita, edited, saved, then edited and saved again,
Krita would save that brush tip over the original brush tip,
leaving a backup file behind, circumventing the versioning system.
This commit ensures that Krita recognizes the need to update the
resource using the resource system.

CCBUG:443875