[ledcmd] Add edit_isolated command.
[ledcmd] Add edit_isolated command.

This implements the bulk of editing the isolated data associated with a
job Definition. Handy for manually tweaking recipes/test scripts/whatever.

R=smut@chromium.org, tandrii@chromium.org

Bug: 1017818
Change-Id: Icc27737d459e87709a5a96e0fd1b018ac73257a6
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/2090431
Commit-Queue: Robbie Iannucci <40f3d43a28ebae3cb819288542e1c84d73d962d5@chromium.org>
Reviewed-by: smut <95deb7aa15d4c615299e47e7688551456568b1fb@google.com>
Auto-Submit: Robbie Iannucci <40f3d43a28ebae3cb819288542e1c84d73d962d5@chromium.org>

luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go