Refactor locale number (#24134)

Before, the `GiteaLocaleNumber.js` was just written as a a drop-in
replacement for old `js-pretty-number`.

Actually, we can use Golang's `text` package to format.

This PR partially completes the TODOs in `GiteaLocaleNumber.js`:

> if we have complete backend locale support (eg: Golang "x/text"
package), we can drop this component.
> tooltip: only 2 usages of this, we can replace it with Golang's
"x/text/number" package in the future.

This PR also helps #24131

Screenshots:

<details>

![image](https://user-images.githubusercontent.com/2114189/232179420-b1b9974b-9d96-4408-b209-b80182c8b359.png)


![image](https://user-images.githubusercontent.com/2114189/232179416-14f36aa0-3f3e-4ac9-b366-7bd3a4464a11.png)

</details>

modules/test/context_tests.go

@@ -18,6 +18,7 @@ import (
 	user_model "code.gitea.io/gitea/models/user"
 	"code.gitea.io/gitea/modules/context"
 	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/translation"
 	"code.gitea.io/gitea/modules/web/middleware"
 
 	chi "github.com/go-chi/chi/v5"
@@ -34,7 +35,7 @@ func MockContext(t *testing.T, path string) *context.Context {
 			Values: make(url.Values),
 		},
 		Resp:   context.NewResponse(resp),
-		Locale: &mockLocale{},
+		Locale: &translation.MockLocale{},
 	}
 	defer ctx.Close()
 
@@ -91,20 +92,6 @@ func LoadGitRepo(t *testing.T, ctx *context.Context) {
 	assert.NoError(t, err)
 }
 
-type mockLocale struct{}
-
-func (l mockLocale) Language() string {
-	return "en"
-}
-
-func (l mockLocale) Tr(s string, _ ...interface{}) string {
-	return s
-}
-
-func (l mockLocale) TrN(_cnt interface{}, key1, _keyN string, _args ...interface{}) string {
-	return key1
-}
-
 type mockResponseWriter struct {
 	httptest.ResponseRecorder
 	size int