[Balance sheet] Add new entry in the Balance sheet table

**Feature description: A user can add a new entry/row in a balance sheet table**

Flow:
1. Go to Main menu > "Extrase de cont" > select a _Balance sheet_ from the _Balance sheet list_ / add new Balance sheet > "Intrări și ieșiri"
2. Click on button “Adaugă linie”
3. User needs to input the details in the first step: [Figma mock-up 1st screen](https://www.figma.com/file/W7ppl5xGFpB3atVWwYL7qN/Alex-(asistentul-bugetar-al-ONG-urilor)?node-id=3124%3A41738)
4. And the second step: [Figma mock-up 2nd acreen](https://www.figma.com/file/W7ppl5xGFpB3atVWwYL7qN/Alex-(asistentul-bugetar-al-ONG-urilor)?type=design&node-id=3124-43838&mode=design&t=zYol5gXqXHwSyOF7-4)

**Actions on Add new entry in a balance sheet table:**
1. A user can add documents by clicking the button [“Încarcă documente”](https://www.figma.com/file/W7ppl5xGFpB3atVWwYL7qN/Alex-(asistentul-bugetar-al-ONG-urilor)?type=design&node-id=3239-47093&mode=design&t=zYol5gXqXHwSyOF7-4) -- issue https://github.com/code4romania/alex-api/issues/13
2. Save the entry **_Figma mock-up to be reviwed_**
3. Add new entry **_Figma mock-up to be reviwed_**
4. Navigate between the two screens by clicking the buttons "Inapoi" and "Mai departe"