swift:chore - Improvements Tests of all Swift Rules

Add improvements for swift rules with scenarios vulnerables and safe codes in yours tests.
Follow the issue #630 for more details.
Notes:
> Why before swift tool using horusec-engine found 16 vulnerabilities and now found only 1?
* Abouts rule HS-SWIFT-14, Before in examples folder this rule is found 11 times
and now is showed only 3 times, because I changed to only get the specific code
`loadHTMLString` avoiding repetition of vulnerabilities.
* About rule HS-SWIFT-20, Before in examples folder this rule is found 5 times
and now is showed only 1 time, because I changed to only get the specific code
`UIWebView\(\)` other thing before it was just UIWebView and
it can generate a lot of false positives and now it does not.

Signed-off-by: wilian <wilian.silva@zup.com.br>