[Sponsor] Edit Sponsor

**Feature description: A user can edit a Sponsor**

Flow:
1. Go to sidebar menu 'Listă sponsori' > in the table, mouse hoover the three vertical dots at the end of each Sponsor's row > click 'Editează'.
2. Opens the 'Adauga sponsor' form in an edit page, with a change:
- The title: 'Editează sponsor' [Figma: Edit sponsor](https://www.figma.com/file/W7ppl5xGFpB3atVWwYL7qN/Alex-(asistentul-bugetar-al-ONG-urilor)?type=design&node-id=5326-63613&mode=design&t=yGbi7eJPp3Yp46MO-4)

**Actions on edit sponsor:**

Edit:
- change sponsor details (issue https://github.com/code4romania/alex-api/issues/4)
- change contact person's details (issue https://github.com/code4romania/alex-api/issues/4)

Save: when saving changes made on a sponsor's details, it will be available in the form “Lista sponsori” with the modified data

Cancel: all the changes done in the fields will be reset to the original values.