Add ValidVolumes config (#226)

Follow https://gitea.com/gitea/act/pulls/60, https://gitea.com/gitea/act/pulls/64

This PR adds the `valid_volumes` configuration. `valid_volumes` is a sequence containing the volumes (including bind mounts) that can be mounted to the container. By default, `valid_volumes` is empty, which means that no volumes can be mounted. Users can specify multiple valid volumes and [glob](https://github.com/gobwas/glob) is supported.

All volumes will be allowed when using `exec` to run workflows locally.

Reviewed-on: https://gitea.com/gitea/act_runner/pulls/226
Reviewed-by: Lunny Xiao <[email protected]>
Reviewed-by: Jason Song <[email protected]>
Co-authored-by: Zettat123 <[email protected]>
Co-committed-by: Zettat123 <[email protected]>

internal/app/cmd/exec.go

@@ -410,6 +410,7 @@ func runExec(ctx context.Context, execArgs *executeArgs) func(cmd *cobra.Command
 			PlatformPicker: func(_ []string) string {
 				return execArgs.image
 			},
+			ValidVolumes: []string{"**"}, // All volumes are allowed for `exec` command
 		}
 
 		if !execArgs.debug {