Fix bug in parsing of hash_many.

This failed
```
hash_many.psd2 r1 r2 into r3 as field;
```
while this passed
```
hash_many.psd2 r1r2 into r3 as field;
```

The problem was the lack of a call to `Sanitizer::parse_whitespaces` between the
two operands.

This PR fixes the problem by systematically skipping whitespace just before each
operand, as done in other parts of the Aleo instructions parser.

Also add a test demonstrating that the previous failing example above now
passes.

synthesizer/program/src/logic/instruction/operation/hash.rs

@@ -379,8 +379,10 @@ impl<N: Network, const VARIANT: u8> Parser for HashInstruction<N, VARIANT> {
             let mut string = string;
 
             for _ in 0..num_operands {
+                // Parse the whitespace from the string.
+                let (next_string, _) = Sanitizer::parse_whitespaces(string)?;
                 // Parse the operand from the string.
-                let (next_string, operand) = Operand::parse(string)?;
+                let (next_string, operand) = Operand::parse(next_string)?;
                 // Update the string.
                 string = next_string;
                 // Push the operand.
@@ -392,8 +394,6 @@ impl<N: Network, const VARIANT: u8> Parser for HashInstruction<N, VARIANT> {
 
         // Parse the opcode from the string.
         let (string, _) = tag(*Self::opcode())(string)?;
-        // Parse the whitespace from the string.
-        let (string, _) = Sanitizer::parse_whitespaces(string)?;
         // Parse the operands from the string.
         let (string, operands) = parse_operands(string, expected_num_operands(VARIANT))?;
         // Parse the whitespace from the string.

synthesizer/tests/expectations/parser/instruction/instruction_pass.out

@@ -61,3 +61,4 @@
 - Parsing was successful.
 - Parsing was successful.
 - Parsing was successful.
+- Parsing was successful.

synthesizer/tests/tests/parser/instruction/instruction_pass.aleo

@@ -33,6 +33,7 @@ hash.ped128 r0 into r1 as u32;
 hash.psd2 r0 into r1 as scalar;
 hash.psd4 r0 into r1 as group;
 hash.psd8 r0 into r1 as address;
+hash_many.psd2 r1 r2 into r3 as field;
 inv r0 into r1;
 is.eq r0 r1 into r2;
 is.neq r0 r1 into r2;