Fix positional arg bug in ExpressionParser.CreateTree

[ericsciple]

allowCaseFunction was passed positionally into the allowUnknownKeywords, causing the legacy parser to silently accept any named-value in expressions during schema validation.

[Copilot]

Pull request overview

Fixes a positional-argument mixup in ExpressionParser.CreateTree that caused allowCaseFunction to incorrectly toggle allowUnknownKeywords, letting invalid named-values slip through schema validation.

Changes:

• Pass allowCaseFunction into ParseContext via a named argument to avoid the incorrect parameter binding.
• Add regression tests for expression parsing and for action manifest parsing (legacy/new/wrapper) to ensure invalid contexts are rejected.
• Add new action manifest test data covering invalid env expression context usage.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/Sdk/DTExpressions2/Expressions2/ExpressionParser.cs	Fixes the root cause by using a named argument for allowCaseFunction when constructing ParseContext.
src/Test/L0/Sdk/ExpressionParserL0.cs	Adds regression tests ensuring unknown named-values are rejected and case() behavior doesn’t affect keyword validation.
src/Test/L0/Worker/ActionManifestParserComparisonL0.cs	Adds a wrapper-level test asserting both parsers reject invalid expression context in container env.
src/Test/L0/Worker/ActionManifestManagerLegacyL0.cs	Adds legacy parser tests for rejecting invalid env contexts and accepting valid ones.
src/Test/L0/Worker/ActionManifestManagerL0.cs	Adds new parser tests for rejecting invalid env contexts and accepting valid ones.
src/Test/TestData/dockerfileaction_env_invalid_context.yml	Adds a manifest fixture that contains a valid and an invalid expression context in runs.env.