Solution_id is integer (#3071)

# Description
Related to #3064

This PR enables driver to send either string or integer for
`solution_id`.

This PR marks the start of transition period. Once the PR is merged,
external solvers will be asked to:
1. Start sending `solution_id` as integer in `/solve` response.
2. Implement receiving either string or integer for `solution_id` on
`/reveal` and on `/settle`.

Once done, backend will have a [follow
up](#3072) where we will
definitely switch to using integers in all three endpoints and
#3064 will be fixed.

## How to test
Manually checked that both versions are properly
serialized/deserialized.

<!--
## Related Issues

Fixes #
-->

crates/autopilot/src/infra/solvers/dto/solve.rs

@@ -170,7 +170,7 @@ pub enum Side {
 pub struct Solution {
     /// Unique ID of the solution (per driver competition), used to identify
     /// it in subsequent requests (reveal, settle).
-    #[serde_as(as = "serde_with::DisplayFromStr")]
+    #[serde(deserialize_with = "deserialize_solution_id")]
     pub solution_id: u64,
     #[serde_as(as = "HexOrDecimalU256")]
     pub score: U256,
@@ -182,6 +182,37 @@ pub struct Solution {
     pub gas: Option<u64>,
 }
 
+fn deserialize_solution_id<'de, D>(deserializer: D) -> Result<u64, D::Error>
+where
+    D: serde::Deserializer<'de>,
+{
+    struct SolutionIdVisitor;
+
+    impl<'de> serde::de::Visitor<'de> for SolutionIdVisitor {
+        type Value = u64;
+
+        fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
+            formatter.write_str("a string or integer representing a solution ID")
+        }
+
+        fn visit_u64<E>(self, value: u64) -> Result<u64, E>
+        where
+            E: serde::de::Error,
+        {
+            Ok(value)
+        }
+
+        fn visit_str<E>(self, value: &str) -> Result<u64, E>
+        where
+            E: serde::de::Error,
+        {
+            value.parse::<u64>().map_err(serde::de::Error::custom)
+        }
+    }
+
+    deserializer.deserialize_any(SolutionIdVisitor)
+}
+
 #[derive(Clone, Debug, Deserialize)]
 #[serde(rename_all = "camelCase", deny_unknown_fields)]
 pub struct Response {

crates/driver/openapi.yml

@@ -382,8 +382,8 @@ components:
                   The unique identifier of the solution.
                   
                   This id is used to identify the solution when executing it.
-                type: string
-                example: "1"
+                type: integer
+                example: 1
               score:
                 description: |
                   The objective value of the solution.

crates/driver/src/infra/api/routes/solve/dto/solved.rs

@@ -70,7 +70,6 @@ type OrderId = [u8; order::UID_LEN];
 pub struct Solution {
     /// Unique ID of the solution (per driver competition), used to identify it
     /// in subsequent requests (reveal, settle).
-    #[serde_as(as = "serde_with::DisplayFromStr")]
     solution_id: u64,
     #[serde_as(as = "serialize::U256")]
     score: eth::U256,

crates/driver/src/tests/setup/mod.rs

@@ -1193,7 +1193,8 @@ impl<'a> SolveOk<'a> {
         solution
             .get("solutionId")
             .unwrap()
-            .as_str()
+            .as_u64()
+            .map(|id| id.to_string())
             .unwrap()
             .to_owned()
     }