Add enablePrattParser option and split Parser into AntlrParser and dispatcher

Split Parser.java into AntlrParser.java (containing all ANTLR dependencies) and Parser.java (acting as a simple dispatcher between AntlrParser and PrattParser).
Refactor CelParserParameterizedTest and CelParserImplTest to run tests against both ANTLR and Pratt parsers to ensure exact AST equivalence.

PiperOrigin-RevId: 978827922

Author: dmitriplotnikov

common/src/main/java/dev/cel/common/CelOptions.java

@@ -72,6 +72,8 @@ public enum ProtoUnsetFieldOptions {
 
   public abstract boolean enableQuotedIdentifierSyntax();
 
+  public abstract boolean enablePrattParser();
+
   // Type-Checker related options
 
   public abstract boolean enableCompileTimeOverloadResolution();
@@ -144,6 +146,7 @@ public static Builder newBuilder() {
         .retainUnbalancedLogicalExpressions(false)
         .enableHiddenAccumulatorVar(true)
         .enableQuotedIdentifierSyntax(true)
+        .enablePrattParser(false)
         // Type-Checker options
         .enableCompileTimeOverloadResolution(false)
         .enableHomogeneousLiterals(false)
@@ -279,6 +282,9 @@ public abstract static class Builder {
      */
     public abstract Builder enableQuotedIdentifierSyntax(boolean value);
 
+    /** Enables Pratt parser implementation over ANTLR parser. */
+    public abstract Builder enablePrattParser(boolean value);
+
     // Type-Checker related options
 
     /**

common/src/test/java/dev/cel/common/CelOptionsTest.java

@@ -35,5 +35,6 @@ public void current_defaults() {
     // Defaults that aren't represented in deprecated CelOptions
     assertThat(CelOptions.current().build().enableUnknownTracking()).isFalse();
     assertThat(CelOptions.current().build().resolveTypeDependencies()).isTrue();
+    assertThat(CelOptions.current().build().enablePrattParser()).isFalse();
   }
 }