Make loading of arguments form project configuration on first start optional

[Irame]

When a solution is opend for the first time (flag in .suo file). There should be two buttons in the extension window. One to load arguments from configurations for each project where no .args.json exists (only if VCS support is active). And a second one to don't load the args from the configuration and only use existing .args.json.

Related issues: #119 #117 #120 #123 #124