compiler, testing: Build System for Compilation

The compilation code was written as a precursor for implementation
with macros. The updates in this commit make the switch.

There is still plenty to do:

1. Comment Walker.
2. Comment Macros.

Signed-off-by: Will Hawkins <hawkinsw@obs.cr>

Tests/p4rseTests/ControlCompilerTests.swift

@@ -107,6 +107,36 @@ import P4Lang
   #expect(#RequireOkResult(Program.Compile(simple_parser_declaration)))
 }
 
+@Test func test_simple_control_declaration_with_multiple_tables() async throws {
+  let simple_parser_declaration = """
+    control simple(bool x, bool y, bool a, bool b) {
+      action a() {
+      }
+      table t {
+        key = {
+          x: exact;
+          y: exact;
+        }
+      }
+      table u {
+        key = {
+          a: exact;
+          b: exact;
+        }
+      }
+      apply {
+      }
+    };
+    """
+  #expect(
+    #RequireErrorResult(
+      Error(
+        withMessage: "{0, 215}: More than one table in control declaration"
+      ),
+      Program.Compile(simple_parser_declaration))
+  )
+}
+
 @Test func test_simple_control_declaration_with_action_using_parameter() async throws {
   let simple_parser_declaration = """
     control simple(bool x, bool y) {
@@ -150,4 +180,36 @@ import P4Lang
       ),
       Program.Compile(simple_parser_declaration))
   )
+}
+
+@Test func test_simple_control_declaration_with_element_after_apply() async throws {
+  let simple_parser_declaration = """
+    control simple(bool x, bool y) {
+      action a(int z) {
+        z = false;
+      }
+      table t {
+        key = {
+          x: exact;
+          y: exact;
+        }
+      }
+      apply {
+      }
+      table x {
+        key = {
+          x: exact;
+          y: exact;
+        }
+      }
+    };
+    """
+  #expect(
+    #RequireErrorResult(
+      Error(
+        withMessage:
+          "Could not compile the P4 program"
+      ),
+      Program.Compile(simple_parser_declaration))
+  )
 }