Update version and manifests v0.12.0

Update version and manifests v0.12.0

Update VERSION to v0.12.0-rc6

Update manifests to v0.12.0-rc5

Update manifests to v0.12.0-rc4

Bump version and manifests to v0.12.0-rc3

Bump version and manifests to v0.12.0-rc2

Sort kustomize params in GetAppDetails

Adds client retry. Fixes argoproj#959 (argoproj#1119)

Fix test compile error (argoproj#1052)