chore: field encoding should use fromString instead of fromHexString (#11585)

Related #10331

Author: sklppy88

yarn-project/foundation/src/abi/encoder.test.ts

@@ -180,7 +180,7 @@ describe('abi/encoder', () => {
     };
     const args = ['garbage'];
 
-    expect(() => encodeArguments(testFunctionAbi, args)).toThrow('Invalid hex-encoded string: "garbage"');
+    expect(() => encodeArguments(testFunctionAbi, args)).toThrow('Tried to create a Fr from an invalid string');
   });
 
   it('throws when passing string argument as integer', () => {

yarn-project/foundation/src/abi/encoder.ts

@@ -50,7 +50,7 @@ class ArgumentEncoder {
         } else if (typeof arg === 'bigint') {
           this.flattened.push(new Fr(arg));
         } else if (typeof arg === 'string') {
-          this.flattened.push(Fr.fromHexString(arg));
+          this.flattened.push(Fr.fromString(arg));
         } else if (typeof arg === 'boolean') {
           this.flattened.push(new Fr(arg ? 1n : 0n));
         } else if (typeof arg === 'object') {