`env` field for options and flags

[github-actions]

Name the environment variable to use as default value on init, if available

qui-cli/packages/plugin/src/Options.ts

Lines 4 to 6 in 6aa6697

	* TODO `env` field for options and flags
	* Name the environment variable to use as default value on init, if available
	*/

import { ConfigMetaSet, ConfigSet, ConfigType } from 'jackspeak';

/*
 * TODO `env` field for options and flags
 *   Name the environment variable to use as default value on init, if available
 */

/*
 * TODO `secret` (or similar) field for options and flags
 *   Indicate that the actual default value should not be displayed in usage (e.g. for an `env` value)
 */

type MetaSet<T extends ConfigType> = {
  value: ConfigMetaSet<T, false>;
  list: ConfigMetaSet<T, true>;

[battis]

Don't forget that flags and nums will need to be parsed out of the environment strings -- can't be the straight value!

[battis]

Thinking on #33, it may be that if a value can be loaded from the environment, that there should be the ability to suppress it as a user-entered command- line option.

[battis]

jackspeak's envPrefix configuration could probably drive this on the implementation level, just need to make the usage() pretty.

[battis]

Intuitively, this is an interplay between @qui-cli/env and @qui-cli/plugin that is creates a circular dependency (undesireable!). The better option is probably to create a new extension hook in @qui-cli/plugin that has to do with processing arguments -- one that could be used to both inject a default value into the options() definition from the environment but also allows for parsing other types from arguments (e.g. regular expressions).