Support creation of dockerconfigjson secret type

[conorfennell]

Current Behaviour:
The lastpass-operator supports the creation of Opaque secrets.

Enhanced behaviour:
Add the flexibility in the LastPass custom resource to choose the type of secret to be created.

type: kubernetes.io/dockerconfigjson
key: .dockerconfigjson

Example secret for docker credentials

apiVersion: v1
kind: Secret
type: kubernetes.io/dockerconfigjson
metadata:
  name: regcred
  namespace: bots
data:
  .dockerconfigjson: ewogICAiYXV0aHMiOnsKICAgICAgImh0dHBzOi8vaW5kZXguZG9ja2VyLmlvL3YxLyI6ewogICAgICAgICAidXNlcm5hbWUiOiJVc2VybmFtZSIsCiAgICAgICAgICJwYXNzd29yZCI6IlBhc3N3MHJkIiwKICAgICAgICAgImVtYWlsIjoic29tZW9uZUBnbWFpbC5jb20iLAogICAgICAgICAiYXV0aCI6IlZYTmxjbTVoYldVNlVHRnpjM2N3Y21RPSIKICAgICAgfQogICB9Cn0=

Example last pass configuration for docker credentials which will be stored as a base64 string under the .dockerconfigjson key

{
   "auths":{
      "https://index.docker.io/v1/":{
         "username":"Username",
         "password":"Passw0rd",
         "email":"someone@gmail.com",
         "auth":"VXNlcm5hbWU6UGFzc3cwcmQ="
      }
   }
}