Terminal setup logic prone to leaving downlevel versions of tools on workstations

**Describe the bug**
Logic used in https://github.com/cloud-native-toolkit/cloud-shell-commands/blob/main/install.sh will skip over existing installs of tools which may be downlevel, e.g. `igc`, `tkn`, `argocd` . This causes issues for users who may have used these tools before on a workstation and will miss out on features needed for the latest release.

**To Reproduce**
Steps to reproduce the behavior:
1. Previously install tools like `tkn` from brew or have used Cloud Native Tookit in the past on a workstation
2. Attempt to setup terminal with `curl -sL shell.cloudnativetoolkit.dev | bash -`

**Expected behavior**

```
igc --version
1.20.0
```

**Actual behavior**

```
igc --version
0.5.4
```

**IBM Cloud**
Select the services and tools affected

- [ ] IBM Kubernetes Service Managed Service
- [ ] Red Hat OpenShift Managed Services
- [ ] Jenkins
- [ ] Tekton
- [ ] SonarQube
- [ ] Pact
- [ ] Artifactory
- [ ] IBM Image Registry

**Desktop (please complete the following information):**
- OS: MacOS
- Browser N/A
- Version 11.4