Add new rule for detecting legacy HTML filtering rule syntax

[scripthunter7]

Deprecate old HTML filtering syntax, and suggest the modern approach. For example

• tag-content should be replaced by contains:

  example.com$$script[tag-content="foo"]

  ↓↓↓ should be fixed as ↓↓↓

  example.com$$script:contains(foo)

• wildcard should be replaced by contains, and glob pattern should be replaced by regular expression:

  example.com$$script[wildcard="*banner*text*"]

  ↓↓↓ should be fixed as ↓↓↓

  example.com$$script:contains(/banner.*text/)

Suggested rule name: no-legacy-html-filtering-syntax

#13 (comment)