Improve Farmer Login Page

[dave-mills]

• update validation and messages to the user when validation fails.

[dave-mills]

@ciara-mc can you add extra details of what's needed here?

[ciara-mc]

When there is a mistake in the phone number of the farm in login, no message displays to say that there is a mismatch between the qr-code and the number. To add a warning message such as “The number is not right, please enter the right number”.

[aroundissa]

Indeed, that will be fine!

[aroundissa]

Warning message: "Nimɔrɔ ma bɛn, aw ka nimɔrɔ bɛnnen don."