Instead of presuming that bash is installed at /bin/bash, use `$PATH`. Official [bash docker container](https://hub.docker.com/_/bash/) installs bash at `/usr/local/bin` and recommends the use of `env`
Currently the bash script that installs Helm is hard-coded to use
openssl sha command but some distros like Debian 9 only have sha1.
Since the popular current distros have sha1 we can switch to that.
Closes(#2859)
If the execution user is already the root user, this avoids requireing
sudo to be installed within the environment. Which might helo in CI
environments.
This adds 'scripts/get`, which is a bash script for fetching and
installing the Helm client. It has the following features:
- It uses the GitHub API to discover the latest release
- It downloads the SHA256 checksum and verifies the binary using it
- It does basic tests on the installation