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:

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

PR Checklist

• [x] PR has meaningful title
• [x] Summary describes changes
• [x] 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.
• [x] 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?

[nohwnd]

The PR looks great. There is some merge conflict