resources/page: Use binary search in Pages.Prev/Next if possible

This is obviously much faster for lager data sets:

```bash
name                         old time/op    new time/op    delta
SearchPage/ByWeight-100-4       267ns ± 4%     272ns ± 5%     ~     (p=0.457 n=4+4)
SearchPage/ByWeight-5000-4     10.8µs ± 3%     1.2µs ± 2%  -88.99%  (p=0.029 n=4+4)
SearchPage/ByWeight-10000-4    21.1µs ± 1%     1.4µs ±11%  -93.28%  (p=0.029 n=4+4)
```

See #4500

1 files changed, 11 insertions, 16 deletions

diff --git a/resources/page/pages_prev_next.go b/resources/page/pages_prev_next.go
index dd87aa4ce..dd767c667 100644
--- a/resources/page/pages_prev_next.go
+++ b/resources/page/pages_prev_next.go
@@ -15,26 +15,21 @@ package page
 
 // Next returns the next page reletive to the given
 func (p Pages) Next(cur Page) Page {
-	for x, c := range p {
-		if c.Eq(cur) {
-			if x == 0 {
-				return nil
-			}
-			return p[x-1]
-		}
+	x := searchPage(cur, p)
+	if x <= 0 {
+		return nil
 	}
-	return nil
+	return p[x-1]
 }
 
 // Prev returns the previous page reletive to the given
 func (p Pages) Prev(cur Page) Page {
-	for x, c := range p {
-		if c.Eq(cur) {
-			if x < len(p)-1 {
-				return p[x+1]
-			}
-			return nil
-		}
+	x := searchPage(cur, p)
+
+	if x == -1 || len(p)-x < 2 {
+		return nil
 	}
-	return nil
+
+	return p[x+1]
+
 }