Fix eslint errors

Related to #1362.
Signed-off-by: Denis Golovin <dgolovin@redhat.com>

Author: dgolovin

src/util/archive.ts

@@ -60,4 +60,4 @@ export class Archive {
             .on('close', resolve);
         });
     }
-}
+}

src/util/constants.ts

@@ -10,5 +10,4 @@ export enum GlyphChars {
     Push = '\u25C9',
     NotPushed = '\u25CE',
     NoContext = '\u2718'
-
-}
+}

src/util/credentialManager.ts

@@ -3,18 +3,35 @@
  *  Licensed under the MIT License. See LICENSE file in the project root for license information.
  *-----------------------------------------------------------------------------------------------*/
 
-import { env, ExtensionContext } from 'vscode';
+ /* eslint-disable import/no-dynamic-require */
+ /* eslint-disable global-require */
+
+ import { env, ExtensionContext } from 'vscode';
+
+ export function getVscodeModule<T>(moduleName: string): T | undefined {
+  try {
+      return require(`${env.appRoot}/node_modules.asar/${moduleName}`);
+  } catch (err) {
+      // Not in ASAR.
+  }
+  try {
+      return require(`${env.appRoot}/node_modules/${moduleName}`);
+  } catch (err) {
+      // Not available.
+  }
+  return undefined;
+}
 
 const keytar: any = getVscodeModule('keytar');
 
 export class TokenStore {
     public static extensionContext: ExtensionContext;
 
-    static async setItem(key: string, login: string, value: string): Promise<void> {
-        return keytar ? keytar.setPassword(key, login, value) : undefined;
+    static setItem(key: string, login: string, value: string): Promise<void> {
+        return keytar ? keytar.setPassword(key, login, value) : Promise.resolve();
     }
 
-    static async getItem(key: string, login: string): Promise<string> {
+    static getItem(key: string, login: string): Promise<string> {
         return keytar ? keytar.getPassword(key, login) : '';
     }
 
@@ -26,17 +43,3 @@ export class TokenStore {
         return TokenStore.extensionContext.globalState.get('username');
     }
 }
-
-export function getVscodeModule<T>(moduleName: string): T | undefined {
-    try {
-        return require(`${env.appRoot}/node_modules.asar/${moduleName}`);
-    } catch (err) {
-        // Not in ASAR.
-    }
-    try {
-        return require(`${env.appRoot}/node_modules/${moduleName}`);
-    } catch (err) {
-        // Not available.
-    }
-    return undefined;
-}