Add more detection patterns on Rails/ResponseParsedBody

[r7kamura]

Added detection patterns to correctly detect some of Nokogiri's aliases as well.

Code	Before	After
JSON.parse(response.body)	bad	bad
Nokogiri::HTML(response.body)	good	bad
Nokogiri::HTML4(response.body)	good	bad
Nokogiri::HTML5(response.body)	good	bad
Nokogiri::HTML.parse(response.body)	bad	bad
Nokogiri::HTML4.parse(response.body)	good	bad
Nokogiri::HTML5.parse(response.body)	bad	bad
Nokogiri::HTML::Document.parse(response.body)	good	bad
Nokogiri::HTML4::Document.parse(response.body)	good	bad
Nokogiri::HTML5::Document.parse(response.body)	good	bad

Note: The originally supported Nokogiri::HTML corresponds to Nokogiri::HTML4, so both HTML4 and HTML5 were originally detected. See docs about more details:

• https://nokogiri.org/rdoc/index.html

---

Additionally, I simplified the offense message. This was done out of concern that optimizing the message might complicate the code, given the increased scope of this implementation.

# Before
Prefer `response.parsed_body` to `Nokogiri::HTML.parse(response.body)`.

# After
Prefer `response.parsed_body`.