Use a different way to check if a tag is annotated

Storing it in the Tag struct makes loading tags a lot slower when there is a
very large number of tags; so determine it on the fly instead. On my machine,
the additional call takes under 5ms, so it seems we can afford it.

pkg/commands/git_commands/tag.go

@@ -1,6 +1,8 @@
 package git_commands
 
 import (
+	"strings"
+
 	"github.com/jesseduffield/gocui"
 	"github.com/jesseduffield/lazygit/pkg/commands/oscommands"
 )
@@ -74,3 +76,13 @@ func (self *TagCommands) ShowAnnotationInfo(tagName string) (string, error) {
 
 	return self.cmd.New(cmdArgs).RunWithOutput()
 }
+
+func (self *TagCommands) IsTagAnnotated(tagName string) (bool, error) {
+	cmdArgs := NewGitCmd("cat-file").
+		Arg("-t").
+		Arg("refs/tags/" + tagName).
+		ToArgv()
+
+	output, err := self.cmd.New(cmdArgs).RunWithOutput()
+	return strings.TrimSpace(output) == "tag", err
+}