test: Refactor mock CSI manager (#18554)

and MockCSIManager to support the call counting
that csi_hook_test expects

instead of implementing csimanager
interfaces in two separate places:
* client/allocrunner/csi_hook_test
* client/csi_endpoint_test

they can both use the same mocks defined in
client/pluginmanager/csimanager/
alongside the actual implementations of them.

also refactor TestCSINode_DetachVolume
to use use it like Node_ExpandVolume
so we can also test the happy path there

testutil/mock_calls.go

@@ -0,0 +1,42 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: BUSL-1.1
+
+package testutil
+
+import (
+	"maps"
+	"sync"
+
+	"github.com/mitchellh/go-testing-interface"
+)
+
+func NewCallCounter() *CallCounter {
+	return &CallCounter{
+		counts: make(map[string]int),
+	}
+}
+
+type CallCounter struct {
+	lock   sync.Mutex
+	counts map[string]int
+}
+
+func (c *CallCounter) Inc(name string) {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	c.counts[name]++
+}
+
+func (c *CallCounter) Get() map[string]int {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	return maps.Clone(c.counts)
+}
+
+func (c *CallCounter) AssertCalled(t testing.T, name string) {
+	t.Helper()
+	counts := c.Get()
+	if _, ok := counts[name]; !ok {
+		t.Errorf("'%s' not called; all counts: %v", counts)
+	}
+}