* When injecting, perform an uninject as a first step
Fixes#1970
The fixture `inject_emojivoto_already_injected.input.yml` is no longer
rejected, so I created the corresponding golden file.
Note that we'll still forbid injection over resources already injected
with third party meshes (Istio, Contour), so now we have
`HasExisting3rdPartySidecars()` to detect that.
* Generalize HasExistingSidecars() to cater for both the auto-injector and
* Convert `linkerd uninject` result format to the one used in `linkerd inject`.
* More updates to the uninject reports. Revert changes to the HasExistingSidecars func.
Signed-off-by: Alejandro Pedraza <alejandro@buoyant.io>
`linkerd inject` was not checking its input for known sidecars and
initContainers.
Modify `linkerd inject` to check for existing sidecars and
initContainers, specifically, Linkerd, Istio, and Contour.
Part of #1516
Signed-off-by: Andrew Seigner <siggy@buoyant.io>