Add Get sFUEL functionality to the sChain page

[dmytrotkk]

Currently there are 2 ways to get sFuel on the chain:

1. Go to the dedicated sFuel station and claim it
2. Go to Bridge section of the SKALE Portal, select required chain as a source or destination and click 'Get sFuel'

It would be useful to have a dedicated 'Get sFuel' button on the chain details page: