opts: deprecate ListOpts.GetAll in favor of ListOpts.GetSlice

The `GetSlice()` function is part of cobra's [cobra.SliceValue] interface,
and duplicates the older `GetAll()` method. This patch deprecates the
`GetAll()` method in favor of `GetSlice()`.

[cobra.SliceValue]: https://pkg.go.dev/github.com/spf13/cobra@v1.9.1#SliceValue

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

opts/opts.go

@@ -80,6 +80,8 @@ func (opts *ListOpts) GetMap() map[string]struct{} {
 }
 
 // GetAll returns the values of slice.
+//
+// Deprecated: use [ListOpts.GetSlice] instead. This method will be removed in a future release.
 func (opts *ListOpts) GetAll() []string {
 	return *opts.values
 }