Add style settings for text alignment in template signature

[wmnnd]

It should be possible to change the alignment of the content of the signature block from center (default) to left or right.

[panoramix360]

@wmnnd can you describe this task a little more so I can tackle this one? 😃

[wmnnd]

Sure! In the styles section, we should add another option under "Signature": Text alignment - where users should be able to choose between left, right, center, and justified alignment. And then that settings should be applied to the signature.

[wmnnd]

Implemented in 8e8ba55e44a3c153aa7a85d151c7ba17125087f6.

[panoramix360]

@wmnnd sorry for not delivering this earlier, I'm still with little time outside work 😢

I'll look into the issues to try to fix one, it's been a while that I didn't use Elixir 😭