Apple Silicon support for Docker

[biggianteye]

Building the application using Docker on Apple Silicon (M1, M2, etc) fails with the following error in the step where it attempts to install Google Chrome:

7.332 + apt-get install -y --force-yes google-chrome-stable --no-install-recommends
7.341 Reading package lists...
7.723 Building dependency tree...
7.805 Reading state information...
7.864 W: --force-yes is deprecated, use one of the options starting with --allow instead.
7.864 E: Unable to locate package google-chrome-stable
------
failed to solve: process "/bin/sh -c set -ex;     wget -q -O - https://dl.google.com/linux/linux_signing_key.pub | apt-key add -     && wget -q -O - https://deb.nodesource.com/gpgkey/nodesource.gpg.key | apt-key add -     && sh -c 'echo \"deb [arch=amd64] http://dl.google.com/linux/chrome/deb/ stable main\" >> /etc/apt/sources.list.d/google.list'     && apt-get update     && apt-get install -y --force-yes google-chrome-stable --no-install-recommends     && rm -rf /var/lib/apt/lists/*" did not complete successfully: exit code: 100

By default, Docker will use images that match the host architecture (ie. linux/arm64/v8 on Apple Silicon). The above apt repo does not have an ARM version of Google Chrome.

This PR addresses the problem by making it explicit that Docker should always use the linux/amd64 versions of images.

It also addresses another Apple Silicon-related error message and a bundler-related warning. See the individual commit messages for more details.

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Note that the main goal of this PR is to get building of the project to complete via Docker.

[biggianteye]

I have rebased this PR against the latest codebar/planner code and tested it on my M1 machine and it still works as expected.

[biggianteye]

@matyikriszta Is there anything I can do to help towards getting this PR merged?