Standalone installer improvements

[jmgrady]

These changes improve the standalone installer as follows:

• This change adds a server option so that installer can be used to setup a NUC (or other device) running as a server. If the server option is specified, then the Combine is configured to start at boot time.
• The Python virtual environment is removed from the installer. This means that more code must be downloaded during the installation but the installer can run on a system that has a version of Python3 installed that is different from the system that was used to create the installer.
• The script to make the installer will now generate the Chart.yaml files from their templates for all of the helm charts before building the packages. Before this change, the installer could only be created from a working directory that had been used to install The Combine previously.

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This change is 

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.73%. Comparing base (b964bca) to head (351de1c).
Report is 20 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3360      +/-   ##
==========================================
+ Coverage   74.64%   74.73%   +0.08%     
==========================================
  Files         280      280              
  Lines       10744    10744              
  Branches     1298     1298              
==========================================
+ Hits         8020     8029       +9     
+ Misses       2357     2350       -7     
+ Partials      367      365       -2     

Flag	Coverage Δ
backend	83.99% <ø> (+0.18%)	⬆️
frontend	66.67% <ø> (ø)

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[imnasnainaec]

Reviewed 4 of 4 files at r1, 1 of 1 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @jmgrady)