Generators/Text: trim code titles

[jrfnl]

Description

As things were, whitespace at the start/end of a title could cause unnecessary line wrapping of the title.

Fixed now.

Includes updated test expectations.

Before

After

Suggested changelog entry

Generators/Text: minor clean up of code title presentation

Related issues/external references

This PR is part of a series of PRs which will add a complete set of tests (and improvements) for the Generator feature.

Also see: #671 and #718.

Types of changes

• 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

• I have checked there is no other PR open for the same change.
• I have read the Contribution Guidelines.
• 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).
• I have added tests to cover my changes.
• I have verified that the code complies with the projects coding standards.
• [Required for new sniffs] I have added XML documentation for the sniff.