#212 Config script should explicitly fail when the bootstrap.env file is not present in the docker folder.

### Description When the `bootstrap.env` file is not present in `docker/bootstrap`, this means that the `bootstrap_certificates` script has not been run. Currently, this leads the `configure` script in `bin` to crash at line 10(pre-this pr. line 15 after this pr). What this pr does is check if the `bootstrap.env` file exists, if it does not it outputs a message requesting the user to run the `bootstrap_certificates` and fails gracefully. If the file is present the script continues as normal. This PR was tested under `shellcheck` and no additional warnings were introduced. ### Testing There are two scenarios that must be tested: when the `bootstrap.env` is present and when it is not. Make sure you do not have the `bootstrap.env` file and run the `configure` from the root. What you should see is the message `bootstrap.env missing! Please run the bootstrap_certificates script.` show up and the script ends after that. To test that it works normally when `bootstrap.env` is present just generate the file by running the `bootstrap_certificates` script and then you can run the `configure` configure script. In this case, the script should run normally as before querying you about your desired configuration information.