Introduce ResourceSets to make loading of resource files more flexible

This MR introduces so called ResourceSets that allow loading Kubernetes manifests either via ConfigMap or from the file system.

Closes #240 (closed)

docs/index.yaml

 apiVersion: v1
 entries:
   theodolite:
+  - apiVersion: v2
+    appVersion: 0.5.1
+    created: "2021-11-12T16:15:01.629937292+01:00"
+    dependencies:
+    - condition: grafana.enabled
+      name: grafana
+      repository: https://grafana.github.io/helm-charts
+      version: 6.17.5
+    - condition: kube-prometheus-stack.enabled
+      name: kube-prometheus-stack
+      repository: https://prometheus-community.github.io/helm-charts
+      version: 12.0.0
+    - condition: cp-helm-charts.enabled
+      name: cp-helm-charts
+      repository: https://soerenhenning.github.io/cp-helm-charts
+      version: 0.6.0
+    - condition: kafka-lag-exporter.enabled
+      name: kafka-lag-exporter
+      repository: https://lightbend.github.io/kafka-lag-exporter/repo/
+      version: 0.6.6
+    description: Theodolite is a framework for benchmarking the scalability stream
+      processing engines.
+    digest: a67374c4cb2b0e8b2d711468364c6b4a486a910bd1c667dbf3c5614e36e0680c
+    home: https://cau-se.github.io/theodolite
+    maintainers:
+    - email: soeren.henning@email.uni-kiel.de
+      name: Sören Henning
+      url: https://www.se.informatik.uni-kiel.de/en/team/soeren-henning-m-sc
+    name: theodolite
+    sources:
+    - https://github.com/cau-se/theodolite
+    type: application
+    urls:
+    - https://github.com/cau-se/theodolite/releases/download/v0.5.1/theodolite-0.5.1.tgz
+    version: 0.5.1
   - apiVersion: v2
     appVersion: 0.5.0
     created: "2021-11-04T17:45:14.153231798+01:00"
@@ -71,4 +106,4 @@ entries:
     urls:
     - https://github.com/cau-se/theodolite/releases/download/v0.4.0/theodolite-0.4.0.tgz
     version: 0.4.0
-generated: "2021-11-04T17:45:14.120866992+01:00"
+generated: "2021-11-12T16:15:01.591258889+01:00"