rebase: update kubernetes to v1.20.0

updated kubernetes packages to latest
release.

Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>

vendor/k8s.io/utils/trace/README.md

@@ -0,0 +1,67 @@
+# Trace
+
+This package provides an interface for recording the latency of operations and logging details
+about all operations where the latency exceeds a limit.
+
+## Usage
+
+To create a trace:
+
+```go
+func doSomething() {
+    opTrace := trace.New("operation", Field{Key: "fieldKey1", Value: "fieldValue1"})
+    defer opTrace.LogIfLong(100 * time.Millisecond)
+    // do something
+}
+```
+
+To split an trace into multiple steps:
+
+```go
+func doSomething() {
+    opTrace := trace.New("operation")
+    defer opTrace.LogIfLong(100 * time.Millisecond)
+    // do step 1
+    opTrace.Step("step1", Field{Key: "stepFieldKey1", Value: "stepFieldValue1"})
+    // do step 2
+    opTrace.Step("step2")
+}
+```
+
+To nest traces:
+
+```go
+func doSomething() {
+    rootTrace := trace.New("rootOperation")
+    defer rootTrace.LogIfLong(100 * time.Millisecond)
+    
+    func() {
+        nestedTrace := rootTrace.Nest("nested", Field{Key: "nestedFieldKey1", Value: "nestedFieldValue1"})
+        defer nestedTrace.LogIfLong(50 * time.Millisecond)
+        // do nested operation
+    }()
+}
+```
+
+Traces can also be logged unconditionally or introspected:
+
+```go
+opTrace.TotalTime() // Duration since the Trace was created
+opTrace.Log() // unconditionally log the trace
+```
+
+### Using context.Context to nest traces
+
+`context.Context` can be used to manage nested traces. Create traces by calling `trace.GetTraceFromContext(ctx).Nest`. 
+This is safe even if there is no parent trace already in the context because `(*(Trace)nil).Nest()` returns
+a top level trace.
+
+```go
+func doSomething(ctx context.Context) {
+    opTrace := trace.FromContext(ctx).Nest("operation") // create a trace, possibly nested
+    ctx = trace.ContextWithTrace(ctx, opTrace) // make this trace the parent trace of the context
+    defer opTrace.LogIfLong(50 * time.Millisecond)
+    
+    doSomethingElse(ctx)
+}
+```