Add environment variable support for select parameters

[cidrblock]

Create a mapping between environment variables and an argparse dest. To preserve a CLI->ENV->default order of precedence we'll look for each of the mapping's option strings in the cli paramters. If provided on the CLI, ignore the enviroment variable. If not provided use an enviroment variable if set.

Environment variable are added to their respective attribute help string.

All ADE specific enviroment variables are prefaced with ADE_ to avoid a conflict with other applicaitons.

This moves and renames the SKIP_UV enviroment variables out to the parser as ADE_UV and adds a command line parameter to match (#278) Backward compatible support was added.

This also revises the use of VIRTUAL_ENV such that it is the enviroment variable for the --venv command line paramter and used if --venv if not provided by the user. (#276). The venv will default to .venv unless VIRTUAL_ENV is set.

This cleans up the NO_COLOR enviroment varaible such that it is now the enviroment variable which cooresponds to the --ansi command line parameter.

Added support for ADE_ISOLATION_MODE mapped to --isolation_mode
Added support for ADE_VERBOSE mapped to -v

Tests updated as needed, largley due the correction of precedense and handling of a non existent venv, as virtual enviroments are now only build when the subcommand is install

Additional tests forthcoming for new code.