feat: add limited type checking for validate command

[kalleep]

PR Description

Doing type checking without evaluation is not easy. But I figured we could start with the simplest case *ast.LiteralExpr.

Because we always know what the values are it's pretty straight forward to add. I also added support for other expressions but it all boils down to performing type checking on Literal expressions.

I also try to handle capsules correctly, where e.g. discovery.Target can be converted into a map.

Which issue(s) this PR fixes

Part of: #3712

Notes to the Reviewer

Next up we can try to type check *ast.AccessExrp but for that we need a bit more information passed and I figured I can to that in a follow up pr.

PR Checklist

• CHANGELOG.md updated
• Documentation added
• Tests updated
• Config converters updated

[Copilot]

Pull request overview

This PR implements limited type checking for the validation command, starting with the simplest case of *ast.LiteralExpr expressions. The implementation includes type checking for literal values, arrays, objects, unary expressions, and binary expressions. The PR also handles capsule types correctly, allowing conversions such as discovery.Target to map types.

Key Changes

• Added comprehensive type checking functions in syntax/typecheck/typecheck.go for various expression types (literal, array, object, unary, binary)
• Refactored binary and unary operation functions from syntax/vm package to a new syntax/internal/transform package for reuse
• Enhanced the value package to expose TryCapsuleConvert and add EncapsulateWithRv for better capsule handling

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
syntax/typecheck/typecheck.go	Added type checking functions for literal, array, object, unary, and binary expressions with proper diagnostic reporting
syntax/typecheck/typecheck_test.go	Extended test suite with new test cases covering wrong literal types, arrays, objects, and capsule type checking
syntax/vm/vm.go	Refactored to use transform.BinaryOp and transform.UnaryOp instead of internal functions
syntax/internal/transform/unary.go	Moved unary operation logic from vm package, renamed function to UnaryOp for public access
syntax/internal/transform/binary.go	Moved binary operation logic from vm package, renamed function to BinaryOp for public access
syntax/internal/value/value.go	Added EncapsulateWithRv function to create capsule values from reflect.Value
syntax/internal/value/decode.go	Made TryCapsuleConvert public and simplified redundant error checking conditions
internal/validator/testdata/default/*.txtar	Updated test data files to use appropriate types for proper validation testing
internal/validator/testdata/default/invalid_types.diags	Added expected diagnostics for new invalid type test cases

[Copilot]

Pull request overview

Copilot reviewed 14 out of 14 changed files in this pull request and generated 5 comments.

Comments suppressed due to low confidence (1)

syntax/internal/value/value.go:105

• The function documentation incorrectly states "Encapsulate panics" when it should say "EncapsulateWithRv panics" to match the actual function name.

// Encode creates a new Value from v. If v is a pointer, v must be considered
// immutable and not change while the Value is used.

[Copilot]

Pull request overview

Copilot reviewed 14 out of 14 changed files in this pull request and generated 1 comment.