Add support for string extraObjects

[PseudoResonance]

Currently, extraObjects only allows YAML inputs, which make it a pain to use templating within them. You can single quote a templated line for most cases, but this doesn't work with multiline things, such as labels.

Example:

labels: {{ include "vm.labels" (dict "helm" . "appKey" "server" "extraLabels" .Values.server.service.labels) | nindent 4 }}

will template as

labels: '
  name: abc
  label2: value'

As shown in this documentation, being able to pass the whole object as a string is great for templating and allows for these multiline strings.

[PseudoResonance]

As a more complete example, I am attempting to add the following to my values.yaml.

extraObjects:
  - |
    {{- $app := .Values.server }}
    {{- $ctx := dict "helm" . "appKey" "server" }}
    apiVersion: v1
    kind: Service
    metadata:
      namespace: {{ include "vm.namespace" . }}
      annotations:
        metallb.universe.tf/address-pool: static-pool
        metallb.universe.tf/loadBalancerIPs: 10.5.0.6,fdde:cdb9:984f:2484:10:5:0:6
      {{- $_ := set $ctx "extraLabels" $app.service.labels }}
      labels: {{ include "vm.labels" $ctx | nindent 4 }}
      {{- $_ := unset $ctx "extraLabels" }}
      name: {{ include "vm.plain.fullname" $ctx }}-syslog
    spec:
      type: LoadBalancer
      externalTrafficPolicy: Local
      ipFamilyPolicy: PreferDualStack
      sessionAffinity: ClientIP
      ports:
        - name: syslog
          port: 514
          targetPort: 514
      selector: {{ include "vm.selectorLabels" $ctx | nindent 4 }}

Along with

server:
  extraArgs:
    syslog.listenAddr.tcp: ":514"
    syslog.listenAddr.udp: ":514"

To allow for ingesting syslogs.

[AndrewChubatiuk]

LGTM! Thanks for contribution!