Add support for lifecycle.preStop.Sleep and bump dependencies

[MatteoMori8]

• As part of this PR we are adding support for lifecycle.preStop.Sleep
• In order to implement this change we had to update the projects dependencies

Special note: cache.NewIndexerInformer is deprecated

• https://pkg.go.dev/k8s.io/client-go/tools/cache#InformerOptions
• Deprecated resource reference: https://pkg.go.dev/k8s.io/client-go/tools/cache#NewIndexerInformer

About CRD changes

• The CRD has been configured to implement some schema validation. The idea is to reduce the load and complexity of the Admission Controller by shifting left on the validation front. For Example:

  • A valid lifecycle.preStop hook, only allows for a single option to be specified. This means that we cannot have both exec and sleep at the same time. This is managed at CRD level making use of oneOf

    oneOf:
    - required: ["exec"]
    - required: ["sleep"]

  Click to example of an Incorrect `dcb` - Not all fields are defined for `exec`

  ---
  apiVersion: vaultwebhook.uswitch.com/v1alpha1
  kind: DatabaseCredentialBinding
  metadata:
    name: a-testing-dcb
    namespace: cloud
  spec:
    database: test
    outputFile: test
    outputPath: /etc/test
    role: readonly
    serviceAccount: test-sa
    container:
      lifecycle:
        preStop:
          exec:
            # Missing 'command:' field

  When applied:

  "a-testing-dcb" is invalid: \
  [<nil>: Invalid value: "": "spec.container.lifecycle.preStop" must validate one and only one schema (oneOf). Found none valid, spec.container.lifecycle.preStop.exec: Required value]

  Click to example of an Incorrect `dcb` - Both `exec` AND `sleep` are specified at the same time

  ---
  apiVersion: vaultwebhook.uswitch.com/v1alpha1
  kind: DatabaseCredentialBinding
  metadata:
    name: a-testing-dcb
  spec:
    database: test
    outputFile: test
    outputPath: /etc/test
    role: readonly
    serviceAccount: test-sa
    container:
      lifecycle:
        preStop:
          sleep:
            seconds: 45
          exec:
            command: [ 'sleep', '60' ]

  When applied:

  The DatabaseCredentialBinding "a-testing-dcb" is invalid: <nil>: Invalid value: "": "spec.container.lifecycle.preStop" 
  must validate one and only one schema (oneOf). Found 2 valid alternatives

• The CRD is implementing a check in lifecycle.preStop.Sleep.seconds to ensure that only positive values are acceptable

  Click to example of an Incorrect `dcb`

  ---
  apiVersion: vaultwebhook.uswitch.com/v1alpha1
  kind: DatabaseCredentialBinding
  metadata:
    name: a-testing-dcb
  spec:
    database: test
    outputFile: test
    outputPath: /etc/test
    role: readonly
    serviceAccount: test-sa
    container:
      lifecycle:
        preStop:
          sleep:
            seconds: -45

  When applied:

  DatabaseCredentialBinding.vaultwebhook.uswitch.com "a-testing-dcb" is invalid: \
  spec.container.lifecycle.preStop.sleep.seconds: Invalid value: -45:  \
  spec.container.lifecycle.preStop.sleep.seconds in body should be greater than or equal to 1