Dockerise and add a csv writer

[thompson318]

A joint pull request addressing #1 and #5. Got slightly jumbled because jeremy/docker was branched off 1-csv-writer rather than dev but OK I think.

Creates a docker container for the waveform-controller and a volume to save the data (similar to the saving of raw hl7 this will result in waveform_data directory belonging to root) We can fix this I think by mounting with a difference username (similar to https://github.com/inform-us/INFORMus/issues/1507#issuecomment-2447767038).

Writes csv data to a new directory caller waveform_data. I file per day per source, currently it looks like about 64Mb per day. Maybe OK in the short term but will need addressing soon.

[jeremyestein]

this will result in waveform_data directory belonging to root) We can fix this I think by mounting with a difference username (similar to inform-us/INFORMus#1507 (comment)).

The fix linked is to do with the build cache — I don't think this will affect what the container does at runtime. If you run it as the GID for "docker" on the GAE it should create files owned by root:docker, which should be readable as long as the root mount dir has been created outside of docker. Ideally we'd also not run as root, but I'm looking into getting a service account set up for that.

Anyway, this can be a separate issue. (opened #14)

[jeremyestein]

Fine, with a few suggestions. Don't mind if they're fixed here or in a separate PR. If we move to parquet, some are not relevant anyway.