Introduce GiteaLocaleNumber custom element to handle number localization on pages. (#23861)

Follow #21429 & #22861

Use `<gitea-locale-number>` instead of backend `PrettyNumber`. All old
`PrettyNumber` related functions are removed. A lot of code could be
simplified.

And some functions haven't been used for long time (dead code), so they
are also removed by the way (eg: `SplitStringAtRuneN`, `Dedent`)

This PR only tries to improve the `PrettyNumber` rendering problem, it
doesn't touch the "plural" problem.

Screenshot:


![image](https://user-images.githubusercontent.com/2114189/229290804-1f63db65-1e34-4a54-84ba-e00b44331b17.png)


![image](https://user-images.githubusercontent.com/2114189/229290911-c88dea00-b11d-48dd-accb-9f52edd73ce4.png)

1 files changed, 0 insertions, 24 deletions

diff --git a/modules/util/truncate.go b/modules/util/truncate.go
index 032a6c0872..f41d27d8b7 100644
--- a/modules/util/truncate.go
+++ b/modules/util/truncate.go
@@ -35,27 +35,3 @@ func SplitStringAtByteN(input string, n int) (left, right string) {
 
 	return input[:end] + utf8Ellipsis, utf8Ellipsis + input[end:]
 }
-
-// SplitStringAtRuneN splits a string at rune n accounting for rune boundaries. (Combining characters are not accounted for.)
-func SplitStringAtRuneN(input string, n int) (left, right string) {
-	if !utf8.ValidString(input) {
-		if len(input) <= n || n-3 < 0 {
-			return input, ""
-		}
-		return input[:n-3] + asciiEllipsis, asciiEllipsis + input[n-3:]
-	}
-
-	if utf8.RuneCountInString(input) <= n {
-		return input, ""
-	}
-
-	count := 0
-	end := 0
-	for count < n-1 {
-		_, size := utf8.DecodeRuneInString(input[end:])
-		end += size
-		count++
-	}
-
-	return input[:end] + utf8Ellipsis, utf8Ellipsis + input[end:]
-}