refactor: drop dead code and use the standard library where it already does the job (#76)

No behaviour change.

- Deleted, unused or one-line wrappers: panes.RuneIndexes, Detail.Refresh (SetDescribed does it), SecretValue.Len, Query.Empty, Clipboard.Native, config.Load, get's value, Model.done, providerOf (cachefile.ProviderOf), contextWithTimeout, searchCoverage, startCrawl, showKeybindings, the expiry aliases and daysLeft.
- cmp.Or instead of the two cmpOr copies; slices.Sorted(maps.Keys(…)), maps.Copy, wg.Go, utf8.RuneCountInString and new(true) instead of loops and helpers that do the same.
- A container's pane title is set once, not twice; a redundant length check in share links and a no-op assignment in linkhandler.Launch are gone.
- Tests call ansi.Strip and lastLines directly; gofmt -s on links.go.

Reviewed-on: #76
Co-authored-by: Karl-Einar Bergstrøm <karl-einarb@outlook.com>

cmd/lazysecrets/main.go

@@ -68,27 +68,20 @@ func checkCommandKeys(km *keys.Map, cmds []commands.Command) error {
 		if c.Key == "" {
 			continue
 		}
-		name := fmt.Sprintf("custom command %q", cmpOr(c.Description, c.Command))
+		name := fmt.Sprintf("custom command %q", cmp.Or(c.Description, c.Command))
 		if err := km.CheckExtra(c.Key, name); err != nil {
 			return err
 		}
 		for _, d := range cmds[:i] {
 			overlap := c.Context == d.Context || c.Context == commands.Global || d.Context == commands.Global
 			if d.Key == c.Key && overlap {
-				return fmt.Errorf("%s: %q is also the key of custom command %q", name, c.Key, cmpOr(d.Description, d.Command))
+				return fmt.Errorf("%s: %q is also the key of custom command %q", name, c.Key, cmp.Or(d.Description, d.Command))
 			}
 		}
 	}
 	return nil
 }
 
-func cmpOr(a, b string) string {
-	if a != "" {
-		return a
-	}
-	return b
-}
-
 // refArg parses get's and open's arguments: a reference, and optionally
 // the account to use when several could (lazysecrets list's column) and,
 // for open, what to do with it rather than asking (--action).