Add a shortcut to get to "my workflows" page

User story

Today I wanted to look at all the workflows I've started. Immediately I tried to go in my users tab in the upper right corner expecting a "My workflows" button together with my user and tokens button, it wasn't there. So I tried my user's page and also nothing. Then I went to workflows and added the "Started By" filter and it worked. I'd say is a very common case to go through one's own workflows, so it'd be nice to have it at most 2 clicks from any page.

Error handling

I can only think in a user not logged in, in that case it shouldn't be displayed "my workflows" button. It's already the current behavior to not have an expandable tab when the user is not logged in.

Implementation plan

TBD

Open questions

• Where this button should be placed is up for debate, I'd like to have it together with "Tokens", "Log out" and my user's profile buttons.

Notes

Somewhat related to #972