--write: Optionally pass rule names to --write in cli

[cognifloyd]

Allow users to control which transforms ansible-lint --write will run.

Introduces write_list config file setting to complement the --write command line option.
Each of these accept special keywords all and none as well as a list of rule ids and rule tags.

• --write defaults to whatever is in the config file. If write_list is not populated in the config file, then --write is effectively the same thing as --write=all.
• --write=all allows all transforms to run.
• --write=none resets the list of transforms so that people can reformat YAML without running any of the transforms.
  You can also use the none keyword to reset the list so you can run only a different set of rules than what is in the config file (as in --write=none,rule-id will run just rule-id even if all is in the config file).
• --write=rule-id adds rule-id to write_list from the config file. If the config file does not populate write_list, then this means only run the transform for rule rule-id.
• --write=rule-tag works just like --write=rule-id but references rule tags instead of rule ids.

Here are some examples that ignore write_list in the config file and selects rules tagged with ansible-2-11-upgrade:

ansible-lint --write none --write ansible-2-11-upgrade
ansible-lint --write none,ansible-2-11-upgrade

This example just adds ansible-2-11-upgrade to write_list from the config file:

ansible-lint --write ansible-2-11-upgrade

[cognifloyd]

This is too long for a help text. It presents as this wall of text:

  --write [WRITE_LIST]  Allow ansible-lint to reformat YAML files and run rule
                        transforms (Reformatting YAML files standardizes
                        spacing, quotes, etc. A rule transform can fix or
                        simplify fixing issues identified by that rule). You
                        can limit the effective rule transforms (the
                        'write_list') by passing a keywords 'all' or 'none' or
                        a comma separated list of rule ids or rule tags. YAML
                        reformatting happens whenever '--write' or '--write='
                        is used. '--write' and '--write=all' are equivalent:
                        they allow all transforms to run. The effective list
                        of transforms comes from 'write_list' in the config
                        file, followed whatever '--write' args are provided on
                        the commandline. '--write=none' resets the list of
                        transforms to allow reformatting YAML without running
                        any of the transforms (ie '--write=none,rule-id' will
                        ignore write_list in the config file and only run the
                        rule-id transform).

I guess the next thing to do is figure out where this might go in the docs and then post a link from the help text.