add feature: amendement field for searching a single amendement based on its uid

This PR provides amendement field which allows a user to look for a single amendement based on its uid.

It also provides the description/documentation for the field and its arguments for the new amendement field and amendements field, which will be useful to give an example on how to document fields and arguments for the API.

code has been submitted after cargo fmt being applied.

web-server/src/main.rs

@@ -198,7 +198,26 @@ graphql_object!(Query: Context |&self| {
         Ok(reunions)
     }
 
-    field amendements(&executor, since: Option<String>, until: Option<String>) -> FieldResult<Vec<&Amendement>> {
+    field amendement(&executor, id: String as "Identifiant (uid) de l'amendement recherché") -> FieldResult<Option<&Amendement>> as "Rechercher un amendement par son identifiant" {
+        let mut amendement: Option<&Amendement> = None;
+
+        for wrapper in &executor.context().amendements_wrappers{
+            for texteleg in &wrapper.textes_et_amendements{
+                for txtleg in &texteleg.texteleg{
+                    for amds in &txtleg.amendements{
+                        for amd in &amds.amendements{
+                            if &amd.uid == &id {
+                                amendement = Some(&amd)
+                            }
+                        }
+                    }
+                }
+            }
+        }
+        Ok(amendement)
+    }
+
+    field amendements(&executor, since: Option<String> as "Date de départ de la recherche des amendements, au format YYYY-MM-DD", until: Option<String> as "Date limite de la recherche des amendements, au format YYYY-MM-DD") -> FieldResult<Vec<&Amendement>> as "Obtenir la liste des amendements, optionnellement en fournissant une date de départ et une date de fin pour la recherche."{
         let mut amendements: Vec<&Amendement> = Vec::new();
         let parse_from_str = NaiveDate::parse_from_str;