Fix issue title rendering and refactor legacy function names (#32703)

Fix #32700, regression of recent markup refactoring

And by the way, clarify many legacy problems:

1. Some "RenderXxx" functions do not really "render", they only call "post processors"
2. Merge "RenderEmoji | RenderCodeBlock", they are all for "simple issue title"

modules/markup/html_internal_test.go

@@ -252,7 +252,7 @@ func TestRender_IssueIndexPattern_NoShortPattern(t *testing.T) {
 	testRenderIssueIndexPattern(t, "!1", "!1", NewTestRenderContext(metas))
 }
 
-func TestRender_RenderIssueTitle(t *testing.T) {
+func TestRender_PostProcessIssueTitle(t *testing.T) {
 	setting.AppURL = TestAppURL
 	metas := map[string]string{
 		"format": "https://someurl.com/{user}/{repo}/{index}",
@@ -260,7 +260,7 @@ func TestRender_RenderIssueTitle(t *testing.T) {
 		"repo":   "someRepo",
 		"style":  IssueNameStyleNumeric,
 	}
-	actual, err := RenderIssueTitle(NewTestRenderContext(metas), "#1")
+	actual, err := PostProcessIssueTitle(NewTestRenderContext(metas), "#1")
 	assert.NoError(t, err)
 	assert.Equal(t, "#1", actual)
 }