Update tests to support Pester 5

[andrewwillett]

Modified the three test files to enable compatibility with Pester 5.

Description

Help.tests.ps1

• Changed assertion syntax to use parameters.
• Wrapped initialisation in BeforeDiscovery { } block (including new $params logic which is unreleased to PSGallery).
• Removed foreach and changed to data-driven tests, i.e. Describe -ForEach $commands
• Removed parameter help and uri foreach loops and changed to data-driven tests in Context loops.
• Fixed (?) $links variable initialisation typo (was $link) line 57
• Moved code to both BeforeDiscovery { } and BeforeAll { } as it is used in both Discovery and Test phases
• Renamed assertion names to use new < > templates

Manifest.tests.ps1

• Changed assertion syntax to use parameters.
• Wrapped initialisation in BeforeAll { }
• Moved some variable declaration / resets (?) into assertion blocks, e.g. $script:changelogVersion = $null

Meta.tests.ps1

• Wrapped initialisation in BeforeAll { }

Related Issue

https://github.com/devblackops/Stucco/issues/18

Motivation and Context

Project did not build/pass test with Pester 5 due to breaking changes.

How Has This Been Tested?

• Created new project using Plaster and all tests passed.
• Applied tests to existing project and all tests generated and passed.
• Not tested backward compatibility with Pester 4 etc

Checklist:

• [X] My code follows the code style of this project.
• [X] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [X] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes.
• [X] All new and existing tests passed.

[devblackops]

Thanks @andrewwillett!

This PR and #20 both update the Pester tests for v5. I'm going to merge this one first, then manually incorporate some of the differences from #20.