Throw on unbound user-provided scriptblocks

[fflaten]

PR Summary

Throws when user provides scriptblocks that are not bound to a session state. They would be executed in Pester's module state which could cause unexpected behaviour.

Examples:

Fix #2411

Checklist:

• Add-AssertionOperator -Test (type: ScriptBlock)
• Add-ShouldOperator -Test (type: ScriptBlock)
• AfterAll -Scriptblock (type: ScriptBlock)
• AfterEach -Scriptblock (type: ScriptBlock)
• BeforeAll -Scriptblock (type: ScriptBlock)
• BeforeDiscovery -ScriptBlock (type: ScriptBlock)
• BeforeEach -Scriptblock (type: ScriptBlock)
• Context -Fixture (type: ScriptBlock)
• Describe -Fixture (type: ScriptBlock)
• InModuleScope -ScriptBlock (type: ScriptBlock)
  • Not applicable as it always overrides session state to specified module
• It -Test (type: ScriptBlock)
• Mock -MockWith (type: ScriptBlock)
  • Already handles unbound scriptblocks. Test added
• Mock -ParameterFilter (type: ScriptBlock)
  • Already handles unbound scriptblocks. Test added
• New-PesterContainer -ScriptBlock (type: ScriptBlock[])
• Should-All -FilterScript (type: ScriptBlock)
• Should-Any -FilterScript (type: ScriptBlock)
• Should-Throw -ScriptBlock (type: ScriptBlock)
• Run.Scriptblock
• Run.Container

PR Checklist

• PR has meaningful title
• Summary describes changes
• PR is ready to be merged
  • If not, use the arrow next to Create Pull Request to mark it as a draft. PR can be marked Ready for review when it's ready.
• Tests are added/update (if required)
• Documentation is updated/added (if required)

[fflaten]

Good or checking too many places?
Can we improve the error somehow? Included a truncated scriptblock string to help identity the source.

Update link to https://pester.dev/docs/migrations/v5-to-v6 (when available) with workaround?