[Feature/Improvement] Set exercises as reps or timmer

**Purpose:** As a user, I would really like to have an option to press a button to continue the workout rather than having just a timmer.

**More details:** Some more details on the feature/improvement.
Although this app is a timmer, I usually add a couple of exercises where I use reps instead of time, so it would be really helpful if there is an option on each exercise to "manually" continue, so the app continues the timmer when I click "reps complete".

**Acceptance Criteria:**
Some other commercial apps have a little button when configuring each exercise to set it as reps or timmer.

I don't know of this this kind request can be considered having in mind it's a timmer (I apologize if this is not the purpose of the app), but I would like to share it because it will open a huge number of possibilities.

Anyway, thanks a lot!