Removed weird hack in the library detector

Previously the libraries detector had to load the single librares
provided via '--library' flag after a Rescan, because the library
manager wasn't able to handle a single folder library. Now it can so we
removed all the tricky machinery.

internal/arduino/builder/internal/detector/detector.go

@@ -638,6 +638,14 @@ func LibrariesLoader(
 			})
 		}
 
+		for _, dir := range libraryDirs {
+			lm.AddLibrariesDir(&librariesmanager.LibrariesDir{
+				Path:            dir,
+				Location:        libraries.Unmanaged,
+				IsSingleLibrary: true,
+			})
+		}
+
 		for _, status := range lm.RescanLibraries() {
 			// With the refactoring of the initialization step of the CLI we changed how
 			// errors are returned when loading platforms and libraries, that meant returning a list of
@@ -647,13 +655,6 @@ func LibrariesLoader(
 			// When we're gonna refactor the legacy package this will be gone.
 			verboseOut.Write([]byte(status.Message()))
 		}
-
-		for _, dir := range libraryDirs {
-			// Libraries specified this way have top priority
-			if err := lm.LoadLibraryFromDir(dir, libraries.Unmanaged); err != nil {
-				return nil, nil, nil, err
-			}
-		}
 	}
 
 	resolver := librariesresolver.NewCppResolver()

internal/arduino/libraries/librariesmanager/librariesmanager.go

@@ -185,25 +185,6 @@ func (lm *LibrariesManager) loadLibrariesFromDir(librariesDir *LibrariesDir) []*
 	return statuses
 }
 
-// LoadLibraryFromDir loads one single library from the libRootDir.
-// libRootDir must point to the root of a valid library.
-// An error is returned if the path doesn't exist or loading of the library fails.
-func (lm *LibrariesManager) LoadLibraryFromDir(libRootDir *paths.Path, location libraries.LibraryLocation) error {
-	if libRootDir.NotExist() {
-		return fmt.Errorf(tr("library path does not exist: %s"), libRootDir)
-	}
-
-	library, err := libraries.Load(libRootDir, location)
-	if err != nil {
-		return fmt.Errorf(tr("loading library from %[1]s: %[2]s"), libRootDir, err)
-	}
-
-	alternatives := lm.Libraries[library.Name]
-	alternatives.Add(library)
-	lm.Libraries[library.Name] = alternatives
-	return nil
-}
-
 // FindByReference return the installed libraries matching the Reference
 // name and version or, if the version is nil, the libraries installed
 // in the installLocation.