Rails Course: Update strong params to use new Rails 8 method

[JoshDevHub]

Because

Rails 8 introduced a slightly different (and better/more secure) syntax for strong parameters (see: rails changelog)

This method is mentioned in their updated Rails guides (which are part of learner's assigned reading) as the preferred way to handle strong parameters. This is causing confusion as there's a discrepancy with what learners read about strong parameters in the lesson vs. in the rails guides. We could point learners to an older version of the guides on that reading, but I think this is a simple enough fix and doesn't introduce any (easily forgettable) maintenance overhead of eventually needing to go back and set the guides back to default/modern state.

This PR

• Updates controllers lesson to use the new #expect syntax.
• Mentions the permit().require() chain as an older alternative that learners may run into.
• Updates other examples of strong parameters throughout the Rails course to use the newer syntax.
• Fixes lint issues in the controllers lesson.
• Introduces small clarification on what exactly params is inside of a controller.

Issue

Closes #29121

Additional Information

Pull Request Requirements

• I have thoroughly read and understand The Odin Project curriculum contributing guide
• The title of this PR follows the location of change: brief description of change format, e.g. Intro to HTML and CSS lesson: Fix link text
• The Because section summarizes the reason for this PR
• The This PR section has a bullet point list describing the changes in this PR
• If this PR addresses an open issue, it is linked in the Issue section
• If any lesson files are included in this PR, they have been previewed with the Markdown preview tool to ensure it is formatted correctly
• If any lesson files are included in this PR, they follow the Layout Style Guide

[KevinMulhern]

🔥 great stuff @JoshDevHub!