Move duplicated YAML parsing (ReadYAMLObjects, ParseManifestFile) and
CRD readiness check (WaitForCRDsEstablished, CollectCRDNames) into a
shared internal/manifestutil package. Both crdinstall and fluxinstall
now import from manifestutil instead of maintaining identical copies.
Replace fluxinstall's time.Sleep(2s) after CRD apply with proper
WaitForCRDsEstablished polling, matching the crdinstall behavior.
Co-Authored-By: Claude <noreply@anthropic.com>
Signed-off-by: Aleksei Sviridkin <f@lex.la>
