Bump Go version to 1.17

[coro]

Summary Of Changes

This PR bumps the version of Go used to compile the manager binary to 1.17.

This also includes the changes to the go.mod file and // +build directives - see the release notes

Local Testing

Please ensure you run the unit, integration and system tests before approving the PR.

To run the unit and integration tests:

$ make unit-tests integration-tests

You will need to target a k8s cluster and have the operator deployed for running the system tests.

For example, for a Kubernetes context named dev-bunny:

$ kubectx dev-bunny
$ make destroy deploy-dev
# wait for operator to be deployed
$ make system-tests

[Zerpet]

Go mod file seems a lot more verbose now 😄