chore: stop treating dirs as having size 128 (#10750)

Resp. directories for the database, and both dirs and symlinks for
`FileInfo.FileSize`. Instead handle it in the UI progress percentage. We
even already have special cases there for deletions, might as well
handle directories just like any other zero-sized needed item there.

This went through the very thorough testing of running it on my laptop,
the migration was applied and it seemed to be working fine after.

---------

Signed-off-by: Simon Frei <freisim93@gmail.com>

internal/db/sqlite/db_test.go

@@ -29,7 +29,6 @@ import (
 const (
 	folderID  = "test"
 	blockSize = 128 << 10
-	dirSize   = 128
 )
 
 func TestBasics(t *testing.T) {
@@ -72,11 +71,11 @@ func TestBasics(t *testing.T) {
 		t.Fatal(err)
 	}
 	const (
-		localSize      = (1+2+3)*blockSize + dirSize
+		localSize      = (1+2+3)*blockSize
 		remoteSize     = (3 + 4 + 5) * blockSize
-		globalSize     = (2+3+3+4+5)*blockSize + dirSize
+		globalSize     = (2+3+3+4+5)*blockSize
 		needSizeLocal  = remoteSize
-		needSizeRemote = (2+3)*blockSize + dirSize
+		needSizeRemote = (2+3)*blockSize
 	)
 
 	t.Run("SchemaVersion", func(t *testing.T) {