refactor: external_metadata -> external.Provider (#3903)

* tests for TopSongs

Signed-off-by: Deluan <deluan@navidrome.org>

* convert to Ginkgo

Signed-off-by: Deluan <deluan@navidrome.org>

* consolidate tests

Signed-off-by: Deluan <deluan@navidrome.org>

* rename external metadata -wip

Signed-off-by: Deluan <deluan@navidrome.org>

* rename external metadata to extdata.Provider

Signed-off-by: Deluan <deluan@navidrome.org>

* refactor tests - wip

Signed-off-by: Deluan <deluan@navidrome.org>

* refactor test helpers

Signed-off-by: Deluan <deluan@navidrome.org>

* remove reflection

Signed-off-by: Deluan <deluan@navidrome.org>

* use mock.Mock

Signed-off-by: Deluan <deluan@navidrome.org>

* refactor

Signed-off-by: Deluan <deluan@navidrome.org>

* fix

Signed-off-by: Deluan <deluan@navidrome.org>

* receive Agents interface in Provider constructor

Signed-off-by: Deluan <deluan@navidrome.org>

* use mock for Agents

Signed-off-by: Deluan <deluan@navidrome.org>

* tests for SimilarSongs

Signed-off-by: Deluan <deluan@navidrome.org>

* remove duplication

Signed-off-by: Deluan <deluan@navidrome.org>

* ArtistImage tests

Signed-off-by: Deluan <deluan@navidrome.org>

* AlbumImage tests

Signed-off-by: Deluan <deluan@navidrome.org>

* fix provider error handling

Signed-off-by: Deluan <deluan@navidrome.org>

* UpdateAlbumInfo tests - wip

Signed-off-by: Deluan <deluan@navidrome.org>

* UpdateAlbumInfo tests - wip

Signed-off-by: Deluan <deluan@navidrome.org>

* refactor

Signed-off-by: Deluan <deluan@navidrome.org>

* refactor

Signed-off-by: Deluan <deluan@navidrome.org>

* refactor

Signed-off-by: Deluan <deluan@navidrome.org>

* UpdateArtistInfo tests - wip

Signed-off-by: Deluan <deluan@navidrome.org>

* clean up

Signed-off-by: Deluan <deluan@navidrome.org>

* refactor

Signed-off-by: Deluan <deluan@navidrome.org>

* fix test descriptions

Signed-off-by: Deluan <deluan@navidrome.org>

* refactor

Signed-off-by: Deluan <deluan@navidrome.org>

* refactor: rename extdata package to external

Signed-off-by: Deluan <deluan@navidrome.org>

---------

Signed-off-by: Deluan <deluan@navidrome.org>

core/external/extdata_suite_test.go

@@ -0,0 +1,17 @@
+package external
+
+import (
+	"testing"
+
+	"github.com/navidrome/navidrome/log"
+	"github.com/navidrome/navidrome/tests"
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+func TestExternal(t *testing.T) {
+	tests.Init(t, false)
+	log.SetLevel(log.LevelFatal)
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "External Suite")
+}