[feat] Add updateRemoteServer endpoint (#5148)

## Context
#4765 

Following investigations
([#5083](https://github.com/twentyhq/twenty/issues/5083)) we decided to
restrict updates of server from which zero tables have been synchronized
only

## How was it tested
Locally with /metadata
1. Updating a database that already has synchronized tables
<img width="1072" alt="Capture d’écran 2024-04-24 à 16 16 05"
src="https://github.com/twentyhq/twenty/assets/51697796/f9a84c34-2dcd-4f3c-b0bc-b710abae5021">

2. Updating a database that has no synchronized tables
<img width="843" alt="Capture d’écran 2024-04-24 à 16 17 28"
src="https://github.com/twentyhq/twenty/assets/51697796/f320fe03-a6bc-4724-bcd0-4e89d3ac31f5">
+ tested that the connection works well

packages/twenty-server/src/engine/api/graphql/workspace-query-builder/factories/foreign-data-wrapper-query.factory.ts

@@ -1,5 +1,7 @@
 import { Injectable } from '@nestjs/common';
 
+import { isDefined } from 'class-validator';
+
 import {
   ForeignDataWrapperOptions,
   RemoteServerType,
@@ -21,6 +23,20 @@ export class ForeignDataWrapperQueryFactory {
     return `CREATE SERVER "${foreignDataWrapperId}" FOREIGN DATA WRAPPER ${name} OPTIONS (${options})`;
   }
 
+  updateForeignDataWrapper({
+    foreignDataWrapperId,
+    foreignDataWrapperOptions,
+  }: {
+    foreignDataWrapperId: string;
+    foreignDataWrapperOptions: Partial<
+      ForeignDataWrapperOptions<RemoteServerType>
+    >;
+  }) {
+    const options = this.buildUpdateOptions(foreignDataWrapperOptions);
+
+    return `ALTER SERVER "${foreignDataWrapperId}" OPTIONS (${options})`;
+  }
+
   createUserMapping(
     foreignDataWrapperId: string,
     userMappingOptions: UserMappingOptions,
@@ -29,6 +45,16 @@ export class ForeignDataWrapperQueryFactory {
     return `CREATE USER MAPPING IF NOT EXISTS FOR CURRENT_USER SERVER "${foreignDataWrapperId}" OPTIONS (user '${userMappingOptions.username}', password '${userMappingOptions.password}')`;
   }
 
+  updateUserMapping(
+    foreignDataWrapperId: string,
+    userMappingOptions: Partial<UserMappingOptions>,
+  ) {
+    const options = this.buildUpdateUserMappingOptions(userMappingOptions);
+
+    // CURRENT_USER works for now since we are using only one user. But if we switch to a user per workspace, we need to change this.
+    return `ALTER USER MAPPING FOR CURRENT_USER SERVER "${foreignDataWrapperId}" OPTIONS (${options})`;
+  }
+
   private buildNameAndOptionsFromType(
     type: RemoteServerType,
     options: ForeignDataWrapperOptions<RemoteServerType>,
@@ -41,6 +67,36 @@ export class ForeignDataWrapperQueryFactory {
     }
   }
 
+  private buildUpdateOptions(
+    options: Partial<ForeignDataWrapperOptions<RemoteServerType>>,
+  ) {
+    const rawQuerySetStatements: string[] = [];
+
+    Object.entries(options).forEach(([key, value]) => {
+      if (isDefined(value)) {
+        rawQuerySetStatements.push(`SET ${key} '${value}'`);
+      }
+    });
+
+    return rawQuerySetStatements.join(', ');
+  }
+
+  private buildUpdateUserMappingOptions(
+    userMappingOptions?: Partial<UserMappingOptions>,
+  ) {
+    const setStatements: string[] = [];
+
+    if (isDefined(userMappingOptions?.username)) {
+      setStatements.push(`SET user '${userMappingOptions?.username}'`);
+    }
+
+    if (isDefined(userMappingOptions?.password)) {
+      setStatements.push(`SET password '${userMappingOptions?.password}'`);
+    }
+
+    return setStatements.join(', ');
+  }
+
   private buildPostgresFDWQueryOptions(
     foreignDataWrapperOptions: ForeignDataWrapperOptions<RemoteServerType>,
   ) {