Deprecate --rules in favor of --rule-patterns

[tarkatronic]

Feature Request

Is your feature request related to a problem? Please describe.

At this point, all tartufo config has been moved into the one central configuration file, except for --rules. In order to keep everything consistent, we should fix this one last one.

Describe the solution you'd like

• Use of the --rules option should present the user with a DeprecationWarning

• New regex patterns should instead be specified in the configuration file as a table of tables, similar to new style entropy exclusion. It would probably look something like

  [tool.tartufo]
  rule-patterns = [
    {name = "Private key", pattern = "---- BEGIN EC PRIVATE KEY ----", path_pattern = "/some/path"}
  ]

  OR

  [[tool.tartufo.rule-patterns]]
  name = "Private key"
  pattern = "---- BEGIN EC PRIVATE KEY ----"
  path_pattern = "/some/path"

• Required keys would be "name" and "pattern"; "path_pattern" would be optional.

As far as the future deprecation path, I see two possibilities:

1. This gets added to main directly, then ported to the v3.x branch, with the --rules option removed entirely in v3.0
2. This gets merged into v3.x, and we decide upon some far future version (likely even v4.0) where the --rules option can be fully removed

The choice is up to the author of the PR!

[tarkatronic]

Fixed in #287