SharedGitlabManager => Add getUserById and ByUsername functions

managers/SharedGitlabManager.ts

-import axios                      from 'axios';
-import SharedConfig               from '../config/SharedConfig';
-import * as GitlabCore            from '@gitbeaker/core';
-import { GitbeakerRequestError }  from '@gitbeaker/requester-utils';
-import { Gitlab, PipelineSchema } from '@gitbeaker/rest';
-import GitlabToken                from '../types/Gitlab/GitlabToken';
-import { StatusCodes }            from 'http-status-codes';
+import axios                                  from 'axios';
+import SharedConfig                           from '../config/SharedConfig';
+import * as GitlabCore                        from '@gitbeaker/core';
+import { GitbeakerRequestError }              from '@gitbeaker/requester-utils';
+import { Gitlab, PipelineSchema, UserSchema } from '@gitbeaker/rest';
+import GitlabToken                            from '../types/Gitlab/GitlabToken';
+import { StatusCodes }                        from 'http-status-codes';
 
 
 class SharedGitlabManager {
@@ -50,6 +50,35 @@ class SharedGitlabManager {
         return response.data;
     }
 
+    public async getUserById(id: number): Promise<UserSchema | undefined> {
+        try {
+            return await this.executeGitlabRequest(async () => {
+                const user = await this.api.Users.show(id);
+
+                return user.id === id ? user : undefined;
+            });
+        } catch ( e ) {
+            return undefined;
+        }
+    }
+
+    public async getUserByUsername(username: string): Promise<UserSchema | undefined> {
+        try {
+            return await this.executeGitlabRequest(async () => {
+                const user = await this.api.Users.all({
+                                                          username: username,
+                                                          maxPages: 1,
+                                                          perPage : 1
+                                                      });
+
+
+                return user.length > 0 && user[0].username === username ? user[0] : undefined;
+            });
+        } catch ( e ) {
+            return undefined;
+        }
+    }
+
     async getRepositoryPipelines(repoId: number, branch: string = 'main'): Promise<Array<PipelineSchema>> {
         return await this.executeGitlabRequest(async () => {
             return await this.api.Pipelines.all(repoId, {