Add fn install & fn uninstall command - #5

# fn install --all --upgrade
Start installing OpenFunction and its dependencies.
Here are the components and corresponding versions to be installed for this installation:
+------------------+---------+
| COMPONENT        | VERSION |
+------------------+---------+
| Keda             | 2.4.0   |
| Knative Serving  | 0.26.0  |
| Cert Manager     | v1.5.4  |
| Ingress Nginx    | 1.1.0   |
| Tekton Pipelines | v0.28.1 |
| Shipwright       | 0.6.0   |
| OpenFunction     | v0.4.0  |
| Dapr             | 1.4.3   |
+------------------+---------+
The following components already exist in the current cluster:
+------------------+---------+
| COMPONENT        | VERSION |
+------------------+---------+
| Keda             |         |
| Knative Serving  |         |
| Ingress Nginx    |         |
| Cert Manager     |         |
| Tekton Pipelines |         |
| Dapr             |         |
+------------------+---------+
You can see the list of components to be installed and the list of components already exist in the cluster.
You have used the `--upgrade` parameter, which means that the installation process will overwrite the components that already exist in the cluster.
Make sure you know what happens when you do this.
Enter 'y' to continue and 'n' to abort:
-> y
🔄  -> INGRESS <- Installing Ingress...
🔄  -> KNATIVE <- Installing Knative Serving...
🔄  -> DAPR <- Installing Dapr...
🔄  -> DAPR <- Downloading Dapr Cli binary...
🔄  -> KEDA <- Installing Keda...
🔄  -> CERTMANAGER <- Installing Cert Manager...
🔄  -> SHIPWRIGHT <- Installing Shipwright...
🔄  -> INGRESS <- Checking if Ingress is ready...
🔄  -> KEDA <- Checking if Keda is ready...
🔄  -> CERTMANAGER <- Checking if Cert Manager is ready...
🔄  -> SHIPWRIGHT <- Checking if Shipwright is ready...
🔄  -> KNATIVE <- Installing Kourier as Knative's gateway...
🔄  -> KNATIVE <- Configuring Knative Serving's DNS...
🔄  -> KNATIVE <- Checking if Knative Serving is ready...
✅  -> CERTMANAGER <- Done!
🔄  -> DAPR <- Initializing Dapr with Kubernetes mode...
✅  -> SHIPWRIGHT <- Done!
✅  -> KNATIVE <- Done!
✅  -> INGRESS <- Done!
✅  -> DAPR <- Done!
✅  -> KEDA <- Done!
🔄  -> OPENFUNCTION <- Installing OpenFunction...
🔄  -> OPENFUNCTION <- Checking if OpenFunction is ready...
✅  -> OPENFUNCTION <- Done!
🚀 Completed in 2m3.638035129s.

~# fn uninstall --all
Start uninstalling OpenFunction and its dependencies.
Here are the components and corresponding versions to be uninstalled for this installation:
+------------------+---------+
| COMPONENT        | VERSION |
+------------------+---------+
| Cert Manager     | v1.5.4  |
| Ingress Nginx    | 1.1.0   |
| Tekton Pipelines | v0.28.1 |
| Shipwright       | 0.6.0   |
| OpenFunction     | v0.4.0  |
| Dapr             | 1.4.3   |
| Keda             | 2.4.0   |
| Knative Serving  | 0.26.0  |
+------------------+---------+
You can see the list of components to be installed and the list of components already exist in the cluster.
You have used the `--upgrade` parameter, which means that the installation process will overwrite the components that already exist in the cluster.
Make sure you know what happens when you do this.
Enter 'y' to continue and 'n' to abort:
-> y
🔄  -> OPENFUNCTION <- Uninstalling OpenFunction...
🔄  -> KNATIVE <- Uninstalling Knative Serving...
🔄  -> DAPR <- Uninstalling Dapr with Kubernetes mode...
🔄  -> KEDA <- Uninstalling Keda...
🔄  -> SHIPWRIGHT <- Uninstalling Tekton Pipeline & Shipwright...
🔄  -> INGRESS <- Uninstalling Ingress...
🔄  -> CERTMANAGER <- Uninstalling Cert Manager...
✅  -> OPENFUNCTION <- Done!
✅  -> DAPR <- Done!
🔄  -> KNATIVE <- Uninstalling Kourier...
✅  -> KEDA <- Done!
✅  -> CERTMANAGER <- Done!
✅  -> KNATIVE <- Done!
✅  -> INGRESS <- Done!
✅  -> SHIPWRIGHT <- Done!
🚀 Completed in 1m21.683329262s.

~# make build
go fmt ./...
/opt/openfunction/fn-cli/bin/goimports -w cmd/ pkg/ testdata/
go vet ./...
CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build  -ldflags "-s -w -X 'main.goversion=go version go1.16.7 linux/amd64'" \
-o ./dist/fn_linux_amd64 cmd/main.go;