feat(storage): generic cache interface (#8628)

# Which Problems Are Solved

We identified the need of caching.
Currently we have a number of places where we use different ways of
caching, like go maps or LRU.
We might also want shared chaches in the future, like Redis-based or in
special SQL tables.

# How the Problems Are Solved

Define a generic Cache interface which allows different implementations.

- A noop implementation is provided and enabled as.
- An implementation using go maps is provided
  - disabled in defaults.yaml
  - enabled in integration tests
- Authz middleware instance objects are cached using the interface.

# Additional Changes

- Enabled integration test command raceflag
- Fix a race condition in the limits integration test client
- Fix a number of flaky integration tests. (Because zitadel is super
fast now!) 🎸 🚀

# Additional Context

Related to https://github.com/zitadel/zitadel/issues/8648

internal/query/instanceindex_enumer.go

@@ -0,0 +1,78 @@
+// Code generated by "enumer -type instanceIndex"; DO NOT EDIT.
+
+package query
+
+import (
+	"fmt"
+	"strings"
+)
+
+const _instanceIndexName = "instanceIndexByIDinstanceIndexByHost"
+
+var _instanceIndexIndex = [...]uint8{0, 17, 36}
+
+const _instanceIndexLowerName = "instanceindexbyidinstanceindexbyhost"
+
+func (i instanceIndex) String() string {
+	if i < 0 || i >= instanceIndex(len(_instanceIndexIndex)-1) {
+		return fmt.Sprintf("instanceIndex(%d)", i)
+	}
+	return _instanceIndexName[_instanceIndexIndex[i]:_instanceIndexIndex[i+1]]
+}
+
+// An "invalid array index" compiler error signifies that the constant values have changed.
+// Re-run the stringer command to generate them again.
+func _instanceIndexNoOp() {
+	var x [1]struct{}
+	_ = x[instanceIndexByID-(0)]
+	_ = x[instanceIndexByHost-(1)]
+}
+
+var _instanceIndexValues = []instanceIndex{instanceIndexByID, instanceIndexByHost}
+
+var _instanceIndexNameToValueMap = map[string]instanceIndex{
+	_instanceIndexName[0:17]:       instanceIndexByID,
+	_instanceIndexLowerName[0:17]:  instanceIndexByID,
+	_instanceIndexName[17:36]:      instanceIndexByHost,
+	_instanceIndexLowerName[17:36]: instanceIndexByHost,
+}
+
+var _instanceIndexNames = []string{
+	_instanceIndexName[0:17],
+	_instanceIndexName[17:36],
+}
+
+// instanceIndexString retrieves an enum value from the enum constants string name.
+// Throws an error if the param is not part of the enum.
+func instanceIndexString(s string) (instanceIndex, error) {
+	if val, ok := _instanceIndexNameToValueMap[s]; ok {
+		return val, nil
+	}
+
+	if val, ok := _instanceIndexNameToValueMap[strings.ToLower(s)]; ok {
+		return val, nil
+	}
+	return 0, fmt.Errorf("%s does not belong to instanceIndex values", s)
+}
+
+// instanceIndexValues returns all values of the enum
+func instanceIndexValues() []instanceIndex {
+	return _instanceIndexValues
+}
+
+// instanceIndexStrings returns a slice of all String values of the enum
+func instanceIndexStrings() []string {
+	strs := make([]string, len(_instanceIndexNames))
+	copy(strs, _instanceIndexNames)
+	return strs
+}
+
+// IsAinstanceIndex returns "true" if the value is listed in the enum definition. "false" otherwise
+func (i instanceIndex) IsAinstanceIndex() bool {
+	for _, v := range _instanceIndexValues {
+		if i == v {
+			return true
+		}
+	}
+	return false
+}