Support `CelOptions.enableComprehension(boolean)` for feature parity with CEL-Cpp

[sergiitk]

Feature request checklist

• There are no issues that match the desired change
• The change is large enough it can't be addressed with a simple Pull Request
• If this is a bug, please file a Bug Report.

Change
To make CEL environment setup consistent across CEL implementations, I propose to add a runtime option equivalent to CEL-cpp InterpreterOptions.enable_comprehension to CEL-Java and CEL-Go (corresponding ticket google/cel-go#1050).

CelOptions.enableComprehension is true by default. Setting it to false will disable comprehension expressions (e.g. exists(), all() -- except has()). Under-the-hood it may simply call comprehensionMaxIterations(0) to disable comprehension expressions, and reset it to the default value to enable them.

Example

private static final CelRuntime CEL_RUNTIME = CelRuntimeFactory
    .standardCelRuntimeBuilder()
    .setOptions(CelOptions.current().enableComprehension(false).build())
    .build();

@Test
public void macros_comprehensionsDisabled() throws Exception {
  CelCompiler CEL_COMPILER = CelCompilerFactory.standardCelCompilerBuilder()
    .addVar("request", SimpleType.ANY)
    .setResultType(SimpleType.BOOL)
    .setStandardMacros(CelStandardMacro.STANDARD_MACROS)
    .build();

  String expr = "size(['foo', 'bar'].map(x, request[x])) == 2";
  CelRuntime.Program program = CEL_RUNTIME.createProgram(CEL_COMPILER.compile(expr).getAst());

  Map<String, ?> input = ImmutableMap.of("request", ImmutableMap.of("foo", "f", "bar", "b"));
  CelEvaluationException celErr = assertThrows(CelEvaluationException.class, () -> program.eval(input));

  assertThat(celErr.getErrorCode()).isEqualTo(CelErrorCode.ITERATION_BUDGET_EXCEEDED);
}

Related
Internal ref: go/grpc-cel-integration