feat(starknet_api): checked mul for gas vector

crates/starknet_api/src/execution_resources.rs

@@ -66,6 +66,10 @@ impl GasAmount {
     pub fn checked_mul(self, rhs: GasPrice) -> Option<Fee> {
         rhs.checked_mul(self)
     }
+
+    pub fn checked_factor_mul(self, factor: u64) -> Option<Self> {
+        self.0.checked_mul(factor).map(Self)
+    }
 }
 
 #[cfg_attr(
@@ -109,6 +113,20 @@ impl GasVector {
         }
     }
 
+    pub fn checked_mul(self, factor: usize) -> Option<Self> {
+        let u64_factor = factor.try_into().ok()?;
+        match (
+            self.l1_gas.checked_factor_mul(u64_factor),
+            self.l1_data_gas.checked_factor_mul(u64_factor),
+            self.l2_gas.checked_factor_mul(u64_factor),
+        ) {
+            (Some(l1_gas), Some(l1_data_gas), Some(l2_gas)) => {
+                Some(Self { l1_gas, l1_data_gas, l2_gas })
+            }
+            _ => None,
+        }
+    }
+
     /// Computes the cost (in fee token units) of the gas vector (panicking on overflow).
     pub fn cost(&self, gas_prices: &GasPriceVector) -> Fee {
         let mut sum = Fee(0);