Make repositories arch-aware

Introduce an arch field that can be used to filter repositories based on
the local architecture.

If arch is provided and matching with the current GOARCH then the
repository is enabled

cmd/install.go

@@ -80,7 +80,6 @@ To force install a package:
 		LuetCfg.GetSolverOptions().Implementation = solver.SingleCoreSimple
 
 		Debug("Solver", LuetCfg.GetSolverOptions().CompactString())
-		repos := installer.SystemRepositories(LuetCfg)
 
 		// Load config protect configs
 		installer.LoadConfigProtectConfs(LuetCfg)
@@ -101,8 +100,8 @@ To force install a package:
 			DownloadOnly:                downloadOnly,
 			Ask:                         !yes,
 			Relaxed:                     relax,
+			PackageRepositories:         LuetCfg.SystemRepositories,
 		})
-		inst.Repositories(repos)
 
 		system := &installer.System{Database: LuetCfg.GetSystemDB(), Target: LuetCfg.GetSystem().Rootfs}
 		err = inst.Install(toInstall, system)