[Balance sheet] Add new Balance sheet

**About Balance Sheet**
A balance sheet is a monthly statement consisting of all the incoming money and all the expenses a CSO has made during a month’s time. Therefore, a CSO may have one or more balance sheets every month in one or more currencies, depending on the number of accounts they have previously registered in the CSO profile.

The balance sheets can be uploaded to the platform in two different ways (1) manually, line by line or (2) in bulk, handling errors post-upload.
Each balance sheet line (income or expense) may be attributed to a contract.
Each balance sheet will also feature the original document, meaning that the CSO can upload a scanned copy of the balance sheet once it operated all the data input, for both reporting and archiving purposes.

**Feature description: A user can add a balance sheet**

Flow:
1. Go to Main menu -> "Extrase de cont" -> "Adaugă extras de cont" or "Listă extrase de cont" and click on "Adaugă extras de cont" [Figma mock-up](https://www.figma.com/file/W7ppl5xGFpB3atVWwYL7qN/Alex-(asistentul-bugetar-al-ONG-urilor)?type=design&node-id=3068-47934&mode=design&t=zYol5gXqXHwSyOF7-4)
2. A new page opens, where the user needs to select the bank account from the dropdown field, select the month and the year from the date picker field
3. Click "Creează extras de cont". [Figma mock-up](https://www.figma.com/file/W7ppl5xGFpB3atVWwYL7qN/Alex-(asistentul-bugetar-al-ONG-urilor)?type=design&node-id=3068-47914&mode=design&t=zYol5gXqXHwSyOF7-4)
4. A new section is displayed below, where the user will configure the new balance sheet, add entries in the table and perform actions on the entries.

**Actions on Add New Balance Sheet**

1. Select rows from the table -- [Figma: Select rows](https://www.figma.com/file/W7ppl5xGFpB3atVWwYL7qN/Alex-(asistentul-bugetar-al-ONG-urilor)?type=design&node-id=3110-40187&mode=design&t=zYol5gXqXHwSyOF7-4) -- (described in issue https://github.com/code4romania/alex-api/issues/11)
2. Add a new line/entry -- [Figma: Add new entry](https://www.figma.com/file/W7ppl5xGFpB3atVWwYL7qN/Alex-(asistentul-bugetar-al-ONG-urilor)?node-id=3124%3A41738) -- (described in issue https://github.com/code4romania/alex-api/issues/12)
3. Add files/documents -- [Figma: Add documents](https://www.figma.com/file/W7ppl5xGFpB3atVWwYL7qN/Alex-(asistentul-bugetar-al-ONG-urilor)?node-id=3124%3A41738) -- (described in the issue https://github.com/code4romania/alex-api/issues/13)
5. Edit a Balance Sheet table entry -- [Figma: Edit a balance sheet entry](https://www.figma.com/file/W7ppl5xGFpB3atVWwYL7qN/Alex-(asistentul-bugetar-al-ONG-urilor)?node-id=3186%3A39617) -- (described in issue https://github.com/code4romania/alex-api/issues/14)
6. View expanded row on a balance sheet -- [Figma: View row details](https://www.figma.com/file/W7ppl5xGFpB3atVWwYL7qN/Alex-(asistentul-bugetar-al-ONG-urilor)?type=design&node-id=3124-44729&mode=design&t=Ozw7edThwNEG1pHw-4) -- described in issue https://github.com/code4romania/alex-api/issues/15
7. Preview a file attached to a balance sheet -- [Figma: Preview file](https://www.figma.com/file/W7ppl5xGFpB3atVWwYL7qN/Alex-(asistentul-bugetar-al-ONG-urilor)?type=design&node-id=3124-44737&mode=design&t=Ozw7edThwNEG1pHw-4) -- described in issue https://github.com/code4romania/alex-api/issues/24
8. Download a file attached to a balance sheet entry -- [Figma: download file](https://www.figma.com/file/W7ppl5xGFpB3atVWwYL7qN/Alex-(asistentul-bugetar-al-ONG-urilor)?node-id=3124%3A44729) -- described in issue https://github.com/code4romania/alex-api/issues/25
9. Download archive with all the files attached to a balance sheet entry -- [Figma: download archive](https://www.figma.com/file/W7ppl5xGFpB3atVWwYL7qN/Alex-(asistentul-bugetar-al-ONG-urilor)?node-id=3124%3A44729) -- described in issue https://github.com/code4romania/alex-api/issues/26
10. Save: User can Save a new balance sheet by clicking on button Save; the Balance Sheet will be listed in the Balance Sheet list ([Figma: Balance Sheet list](https://www.figma.com/file/W7ppl5xGFpB3atVWwYL7qN/Alex-(asistentul-bugetar-al-ONG-urilor)?type=design&node-id=3068-48233&mode=design&t=zYol5gXqXHwSyOF7-4))
Conditions: * Selecting all the mandatory info in the first step - the account and the date

**_Some details on the three vertical dots at the end of each row > notes in Figma would be nice_**