(GH-11811) Use PascalCase for switch parameters

[michaeltlombardi]

PR Summary

Prior to this change, the casing for the parameters to the switch keyword was inconsistently documented. This change:

• Updates examples, syntax blocks, and prose to use the PascalCase for the parameters, not lowercase.
• Fixes Establish the official switch statement parameter case (PascalCase vs lowercase) #11811

PR Checklist

• Descriptive Title: This PR's title is a synopsis of the changes it proposes.
• Summary: This PR's summary describes the scope and intent of the change.
• Contributor's Guide: I have read the contributors guide.
• Style: This PR adheres to the style guide.

[learn-build-service-prod]

Learn Build status updates of commit 6025976:

✅ Validation status: passed

File	Status	Preview URL	Details
reference/5.1/Microsoft.PowerShell.Core/About/about_Break.md	✅Succeeded	View (powershell-5.1)
reference/5.1/Microsoft.PowerShell.Core/About/about_Language_Keywords.md	✅Succeeded	View (powershell-5.1)
reference/5.1/Microsoft.PowerShell.Core/About/about_Regular_Expressions.md	✅Succeeded	View (powershell-5.1)
reference/7.4/Microsoft.PowerShell.Core/About/about_Break.md	✅Succeeded	View (powershell-7.4)
reference/7.4/Microsoft.PowerShell.Core/About/about_Language_Keywords.md	✅Succeeded	View (powershell-7.4)
reference/7.5/Microsoft.PowerShell.Core/About/about_Break.md	✅Succeeded	View (powershell-7.5)
reference/7.5/Microsoft.PowerShell.Core/About/about_Language_Keywords.md	✅Succeeded	View (powershell-7.5)
reference/7.6/Microsoft.PowerShell.Core/About/about_Language_Keywords.md	✅Succeeded	View (powershell-7.6)
reference/docs-conceptual/lang-spec/chapter-08.md	✅Succeeded	View (>=powershell-5.1)
reference/docs-conceptual/lang-spec/chapter-15.md	✅Succeeded	View (>=powershell-5.1)
reference/docs-conceptual/learn/deep-dives/everything-about-switch.md	✅Succeeded	View (>=powershell-5.1)

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