Adjust wording and layout of Sessions and App passwords personal settings

[jancborchardt]

• changed headers from bold to half-transparent. The important info is the content, not the headers. (See Files app.)
• adjusted padding to be flush to the left with rest
• adjusted wording to be shorter so it works on mobile without a scrollbar
• shortened explanatory texts
• capped overall width to be maximally the width of the sync apps icons so it’s visually balanced and not all over the place on large screens

Please review @nextcloud/designers @ChristophWurst

Before & after:

[mention-bot]

@jancborchardt, thanks for your PR! By analyzing the annotation information on this pull request, we identified @ChristophWurst, @MorrisJobke and @DeepDiver1975 to be potential reviewers

[MorrisJobke]

Tested and looks good. In combination with #438 this is really great 👍

[icewind1991]

👍