Add package buildtimestamp and luet upgrade --sync

Annotate the package build time when compiling, and use that from the
client to force upgrade of packages that changed the artifact, but
didn't changed any version.

The client can trigger this behavior with `luet upgrade --sync`

cmd/upgrade.go

@@ -62,6 +62,7 @@ var upgradeCmd = &cobra.Command{
 		full, _ := cmd.Flags().GetBool("full")
 		universe, _ := cmd.Flags().GetBool("universe")
 		clean, _ := cmd.Flags().GetBool("clean")
+		sync, _ := cmd.Flags().GetBool("sync")
 
 		LuetCfg.GetSolverOptions().Type = stype
 		LuetCfg.GetSolverOptions().LearnRate = float32(rate)
@@ -78,6 +79,7 @@ var upgradeCmd = &cobra.Command{
 			NoDeps:                     nodeps,
 			SolverUpgrade:              universe,
 			RemoveUnavailableOnUpgrade: clean,
+			UpgradeNewRevisions:        sync,
 		})
 		inst.Repositories(repos)
 		_, err := inst.SyncRepositories(false)
@@ -115,6 +117,7 @@ func init() {
 	upgradeCmd.Flags().Bool("full", true, "Attempts to remove as much packages as possible which aren't required (slow)")
 	upgradeCmd.Flags().Bool("universe", false, "Use ONLY the SAT solver to compute upgrades (experimental)")
 	upgradeCmd.Flags().Bool("clean", false, "Try to drop removed packages (experimental, only when --universe is enabled)")
+	upgradeCmd.Flags().Bool("sync", false, "Upgrade packages with new revisions (experimental)")
 
 	RootCmd.AddCommand(upgradeCmd)
 }