Configure Vagrant to use qmk_base_container (#6194)

* Initial conversion of vagrant to use qmkfm/base_container

* Fix vagrant when using docker provider

* Workaround for VirtualBox VM restarts

* Generalise Vagrant docs slightly and add FAQ

util/vagrant/Dockerfile

@@ -0,0 +1,33 @@
+FROM qmkfm/base_container
+
+# Basic upgrades; install sudo and SSH.
+RUN apt-get update && apt-get install --no-install-recommends -y \
+        sudo \
+        openssh-server \
+    && rm -rf /var/lib/apt/lists/*
+RUN mkdir /var/run/sshd
+RUN sed -i 's/PermitRootLogin yes/PermitRootLogin no/' /etc/ssh/sshd_config
+RUN echo 'UseDNS no' >> /etc/ssh/sshd_config
+
+# Remove the policy file once we're finished installing software.
+# This allows invoke-rc.d and friends to work as expected.
+RUN rm /usr/sbin/policy-rc.d
+
+# Add the Vagrant user and necessary passwords.
+RUN groupadd vagrant
+RUN useradd -c "Vagrant" -g vagrant -d /home/vagrant -m -s /bin/bash vagrant
+RUN echo 'root:vagrant' | chpasswd
+RUN echo 'vagrant:vagrant' | chpasswd
+
+# Allow the vagrant user to use sudo without a password.
+RUN echo 'vagrant ALL=(ALL) NOPASSWD: ALL' > /etc/sudoers.d/vagrant
+
+# Install Vagrant's insecure public key so provisioning and 'vagrant ssh' work.
+RUN mkdir /home/vagrant/.ssh
+ADD https://raw.githubusercontent.com/mitchellh/vagrant/master/keys/vagrant.pub /home/vagrant/.ssh/authorized_keys
+RUN chmod 0600 /home/vagrant/.ssh/authorized_keys
+RUN chown -R vagrant:vagrant /home/vagrant/.ssh
+RUN chmod 0700 /home/vagrant/.ssh
+
+EXPOSE 22
+CMD ["/usr/sbin/sshd", "-D"]

util/vagrant/readme.md

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+# QMK Vagrant Utilities
+
+## Dockerfile
+Vagrant-friendly `qmkfm/base_container`.
+
+In order for the Docker provider and `vagrant ssh` to function the container has a few extra requirements.
+
+* vagrant user
+* ssh server
+  * configured with expected public key
+* sudo
+  * passwordless for vagrant user