Revert vendor directory to support old golang (GOPATH mode)

gomodule is still in progress to migrate for now, hence multus
team decide to keep vendor directory to support build without
gomodule.

vendor/github.com/onsi/gomega/internal/oraclematcher/oracle_matcher.go

@@ -0,0 +1,25 @@
+package oraclematcher
+
+import "github.com/onsi/gomega/types"
+
+/*
+GomegaMatchers that also match the OracleMatcher interface can convey information about
+whether or not their result will change upon future attempts.
+
+This allows `Eventually` and `Consistently` to short circuit if success becomes impossible.
+
+For example, a process' exit code can never change.  So, gexec's Exit matcher returns `true`
+for `MatchMayChangeInTheFuture` until the process exits, at which point it returns `false` forevermore.
+*/
+type OracleMatcher interface {
+	MatchMayChangeInTheFuture(actual interface{}) bool
+}
+
+func MatchMayChangeInTheFuture(matcher types.GomegaMatcher, value interface{}) bool {
+	oracleMatcher, ok := matcher.(OracleMatcher)
+	if !ok {
+		return true
+	}
+
+	return oracleMatcher.MatchMayChangeInTheFuture(value)
+}