feat!: add Rego Virtual Machine (RVM) implementation (#495)

* feat!: add Rego Virtual Machine (RVM) implementation

This commit introduces a register-based virtual machine for executing Rego
policies with bytecode-style instructions. Unlike the existing tree-walking
interpreter, the RVM compiles policies into instruction sequences that operate
on virtual registers, offering better performance and optimization potential.

Core Components:

Instruction Set Architecture:
- Define instruction types for data operations, control flow, and builtins
- Implement instruction parameter encoding and display formatting
- Add instruction parser with comprehensive test coverage

Virtual Machine Engine:
- Register-based execution model with program counter management
- Loop execution supporting iterators, comprehensions, and quantifiers
- Function call handling with argument evaluation and context management
- Rule evaluation with default value resolution and virtual data support
- Arithmetic and comparison operation implementations

Program Representation:
- Program listing builder with instruction sequencing
- Rule tree construction for organizing policy rules
- Binary and JSON serialization for compiled programs
- Recompilation support for program modification

Testing Infrastructure:
- Extensive YAML test suites covering all VM features
- Rust unit tests for VM execution and instruction parsing
- Test suites for loops, comprehensions, builtins, and control flow

BREAKING CHANGE: Introduces new VM execution path alongside interpreter

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

* docs: add detailed RVM architecture references

Introduce architecture.md explaining program artifacts, serialization, and runtime subsystems.
Document the full opcode catalog in instruction-set.md, including operands, parameter tables, and outcomes.
Walk through execution flow, stacks, and operational guidance in vm-runtime.md, tying the runtime to the new architecture docs.

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

---------

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

tests/rvm/vm/suites/invalid_collection_ops.yaml

@@ -0,0 +1,61 @@
+# Invalid Collection Operations Test Suite
+# Exercises error conditions for collection-specific instructions.
+
+cases:
+  - note: object_set_on_non_object
+    description: ObjectSet on non-object register triggers error
+    literals:
+      - 1
+      - "key"
+    instructions:
+      - "Load { dest: 0, literal_idx: 0 }"
+      - "Load { dest: 1, literal_idx: 1 }"
+      - "ObjectSet { obj: 0, key: 1, value: 1 }"
+    want_error: "Register 0 does not contain an object"
+
+  - note: array_push_on_non_array
+    description: ArrayPush on scalar register fails
+    literals:
+      - 1
+      - 2
+    instructions:
+      - "Load { dest: 0, literal_idx: 0 }"
+      - "Load { dest: 1, literal_idx: 1 }"
+      - "ArrayPush { arr: 0, value: 1 }"
+    want_error: "Register 0 does not contain an array"
+
+  - note: set_add_on_non_set
+    description: SetAdd on scalar register fails
+    literals:
+      - 1
+      - 2
+    instructions:
+      - "Load { dest: 0, literal_idx: 0 }"
+      - "Load { dest: 1, literal_idx: 1 }"
+      - "SetAdd { set: 0, value: 1 }"
+    want_error: "Register 0 does not contain a set"
+
+  - note: object_create_invalid_template
+    description: ObjectCreate fails when template literal is not object
+    literals:
+      - []
+    instruction_params:
+      object_create_params:
+        - dest: 0
+          template_literal_idx: 0
+          literal_key_fields: []
+          fields: []
+    instructions:
+      - "ObjectCreate { params_index: 0 }"
+    want_error: "ObjectCreate: template is not an object"
+
+  - note: contains_on_scalar_returns_false
+    description: Contains on scalar should return false
+    literals:
+      - 1
+    instructions:
+      - "Load { dest: 0, literal_idx: 0 }"
+      - "Load { dest: 1, literal_idx: 0 }"
+      - "Contains { dest: 2, collection: 0, value: 1 }"
+      - "Return { value: 2 }"
+    want_result: false