Generic/InlineControlStructure: fix two bugs and improve code coverage

[rodrigoprimo]

Description

This PR makes a few changes to the Generic.ControlStructures.InlineControlStructure sniff:

• Fixes a bug when handling else if statements (daa1940b80f6de71d3233f17c59e7d47bfb25960) and another one when handling elseif/if/foreach without a body (716cbf6f257fddec19c2e162f6458c038ca16220).
• Removes two unreachable conditions (2371f216f7826cf570ebb4ceccf1112639d447ff and 42e2f04d267d2453b2a2d5c599464bd8affcfe52).
• Removes a redundant condition (42e2f04d267d2453b2a2d5c599464bd8affcfe52).
• Removes T_SWITCH from the list of tokens that this sniff listens to (3db1049adc9aaf3b5d4f13064e3311e89362f029).
• Improves the code coverage for this sniff (62637cae5238c1b18527ddae0d126a3abf702e11)

While working on this PR, I noticed that the sniff does not handle well a few syntax errors related to the do-while control structure. I will open a separate issue describing what I found.

Suggested changelog entry

Generic.ControlStructures.InlineControlStructure: properly handle else if statements where there is a comment between else and if Generic.ControlStructures.InlineControlStructure: fix false positives when handling elseif, if, and foreach without a body

Related issues/external references

Part of https://github.com/PHPCSStandards/PHP_CodeSniffer/issues/146

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
  • [ ] This change is only breaking for integrators, not for external standards or end-users.
• [ ] Documentation improvement

PR checklist

• [x] I have checked there is no other PR open for the same change.
• [x] I have read the Contribution Guidelines.
• [x] I grant the project the right to include and distribute the code under the BSD-3-Clause license (and I have the right to grant these rights).
• [x] I have added tests to cover my changes.
• [x] I have verified that the code complies with the projects coding standards.
• [ ] [Required for new sniffs] I have added XML documentation for the sniff.