feat: Add stripos to modernize_strpos rule

[antoniovj1]

#6419

Adds stripos to modernize_strpos rule

[coveralls]

coverage: 95.653% (-0.06%) from 95.715%
when pulling 7c503cf on antoniovj1:master
into 731fdd2 on PHP-CS-Fixer:master.

[antoniovj1]

I've added namespaces to strtolower because str_starts_with has it. Does that make sense?

[antoniovj1]

@mvorisek You don't like the implementation or the rule itself (or both 🤣)?

If it is the implementation, feel free to comment, it is the first time that I work on this type of thing and there are probably errors😅

If it is about the rule, you may be able to contribute something in the issue #6419

[mvorisek]

I agree stripos is not much readable but the rule will generate slower code... It should be probably under an option and not enabled by default.

[antoniovj1]

Makes sense @mvorisek ! I will add the possibility to configure it

@Wirone Do you have some proposals for configuration option name?

[antoniovj1]

@mvorisek @Wirone Finally I have added a configuration called modernize_stripos, disabled by default 👍