Styling changes linked to document conversion

[lusebille]

Linked to #1015

As everything is explained on figma https://www.figma.com/design/wcpetFt6aOKzTszcvPPWLQ/%5B05%2F24%5D-Grist-Design?node-id=559-80548&t=qX4iHFYd8uzsW8kZ-1, some styling adjustments are needed and due to this new user journey.

1. Adjust width of the container > up to 750px to make sure all content is readable in all languages (today it's not okay, content is 'jumping' to the next line

2. SELECTION POPUP : Make the blocks in the selection popup more accessible and have a coherent design :

• 1° put the same radio button everywhere ( the rounded one , not the 'check' sign one ), today they're different radio buttons used in Grist (look on figma link)
• 2° Put a 2px 'light green' border for the selected block , today nothing apart the radio button indicates the selection
• 3° Centered the radio button vertically into the block to make more efficient the all block is selected, not only the title
• 4° Align 'cancel' and 'confirm' buttons on the right as it's more common and intuitive for user to click right down to validate

[fflorent]

A patch has been made by @hexaltation and is ready to be submitted in a PR when #1015 is merged.