cache pathExistence

This commit caches the pathExistence of the data folder and user data
folder in order to avoid accessing the disk on every call of
`createConfigDirUri`. This should prevent possible performance
regressions.

Signed-off-by: Vlad Arama <vlad.arama@ericsson.com>

Author: Vlad Arama

packages/core/src/node/env-variables/env-variables-server.ts

@@ -62,7 +62,6 @@ export class EnvVariablesServerImpl implements EnvVariablesServer {
             }
         } else {
             process.env.THEIA_CONFIG_DIR = join(homedir(), '.theia');
-            this.pathExistenceCache[process.env.THEIA_CONFIG_DIR] = true;
         }
         return FileUri.create(process.env.THEIA_CONFIG_DIR).toString();
     }