[chore] media and emoji refactoring (#3000)

* start updating media manager interface ready for storing attachments / emoji right away

* store emoji and media as uncached immediately, then (re-)cache on Processing{}.Load()

* remove now unused media workers

* fix tests and issues

* fix another test!

* fix emoji activitypub uri setting behaviour, fix remainder of test compilation issues

* fix more tests

* fix (most of) remaining tests, add debouncing to repeatedly failing media / emojis

* whoops, rebase issue

* remove kim's whacky experiments

* do some reshuffling, ensure emoji uri gets set

* ensure marked as not cached on cleanup

* tweaks to media / emoji processing to handle context canceled better

* ensure newly fetched emojis actually get set in returned slice

* use different varnames to be a bit more obvious

* move emoji refresh rate limiting to dereferencer

* add exported dereferencer functions for remote media, use these for recaching in processor

* add check for nil attachment in updateAttachment()

* remove unused emoji and media fields + columns

* see previous commit

* fix old migrations expecting image_updated_at to exists (from copies of old models)

* remove freshness checking code (seems to be broken...)

* fix error arg causing nil ptr exception

* finish documentating functions with comments, slight tweaks to media / emoji deref error logic

* remove some extra unneeded boolean checking

* finish writing documentation (code comments) for exported media manager methods

* undo changes to migration snapshot gtsmodels, updated failing migration to have its own snapshot

* move doesColumnExist() to util.go in migrations package

1 files changed, 5 insertions, 4 deletions

diff --git a/internal/api/client/admin/emojiupdate_test.go b/internal/api/client/admin/emojiupdate_test.go
index 676363e39..11beaeaa9 100644
--- a/internal/api/client/admin/emojiupdate_test.go
+++ b/internal/api/client/admin/emojiupdate_test.go
@@ -20,6 +20,7 @@ package admin_test
 import (
 	"context"
 	"encoding/json"
+	"io"
 	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
@@ -370,10 +371,10 @@ func (suite *EmojiUpdateTestSuite) TestEmojiUpdateModifyRemoteEmoji() {
 	defer result.Body.Close()
 
 	// check the response
-	b, err := ioutil.ReadAll(result.Body)
+	b, err := io.ReadAll(result.Body)
 	suite.NoError(err)
 
-	suite.Equal(`{"error":"Bad Request: emoji 01GD5KP5CQEE1R3X43Y1EHS2CW is not a local emoji, cannot update it via this endpoint"}`, string(b))
+	suite.Equal(`{"error":"Bad Request: cannot modify remote emoji"}`, string(b))
 }
 
 func (suite *EmojiUpdateTestSuite) TestEmojiUpdateModifyNoParams() {
@@ -440,7 +441,7 @@ func (suite *EmojiUpdateTestSuite) TestEmojiUpdateCopyLocalToLocal() {
 	b, err := ioutil.ReadAll(result.Body)
 	suite.NoError(err)
 
-	suite.Equal(`{"error":"Bad Request: emoji 01F8MH9H8E4VG3KDYJR9EGPXCQ is not a remote emoji, cannot copy it to local"}`, string(b))
+	suite.Equal(`{"error":"Bad Request: target emoji is not remote; cannot copy to local"}`, string(b))
 }
 
 func (suite *EmojiUpdateTestSuite) TestEmojiUpdateCopyEmptyShortcode() {
@@ -541,7 +542,7 @@ func (suite *EmojiUpdateTestSuite) TestEmojiUpdateCopyShortcodeAlreadyInUse() {
 	b, err := ioutil.ReadAll(result.Body)
 	suite.NoError(err)
 
-	suite.Equal(`{"error":"Conflict: emoji with shortcode rainbow already exists on this instance"}`, string(b))
+	suite.Equal(`{"error":"Conflict: emoji with shortcode already exists"}`, string(b))
 }
 
 func TestEmojiUpdateTestSuite(t *testing.T) {