[feature] configurable maximum thumbnail dimensions (#4258)

- adds configuration for thumbnail maximum dimensions with warning on exceeding recommendations
- moves the media configuration vars into their own sub-struct
- replaces the configuration flag funcs with simple string consts

Reviewed-on: https://codeberg.org/superseriousbusiness/gotosocial/pulls/4258
Reviewed-by: tobi <kipvandenbos@noreply.codeberg.org>
Co-authored-by: kim <grufwub@gmail.com>
Co-committed-by: kim <grufwub@gmail.com>

internal/db/bundb/bundb.go

@@ -376,7 +376,7 @@ func sqliteConn(ctx context.Context) (*sql.DB, func() schema.Dialect, error) {
 	// validate db address has actually been set
 	address := config.GetDbAddress()
 	if address == "" {
-		return nil, nil, fmt.Errorf("'%s' was not set when attempting to start sqlite", config.DbAddressFlag())
+		return nil, nil, fmt.Errorf("'%s' was not set when attempting to start sqlite", config.DbAddressFlag)
 	}
 
 	// Build SQLite connection address with prefs.

internal/db/bundb/migrations/20220612091800_duplicated_media_cleanup.go

@@ -65,7 +65,7 @@ func init() {
 
 		storageBasePath := config.GetStorageLocalBasePath()
 		if storageBasePath == "" {
-			return fmt.Errorf("%s must be set to do storage migration", config.StorageLocalBasePathFlag())
+			return fmt.Errorf("%s must be set to do storage migration", config.StorageLocalBasePathFlag)
 		}
 
 		return db.RunInTx(ctx, nil, func(ctx context.Context, tx bun.Tx) error {