style: Preferences page tweaks

[jessicaschilling]

Assorted fixes to the prefs page:

• The big reset button is now in its own section (instead of under Experiments)
• Updated "open in new window" icon for "read more" links to match the ones for pinning services UI added to ipfs-css: see Adds link_external icons ipfs-shipyard/ipfs-css#43
• Tweaks language throughout prefs page for clarity

[jessicaschilling]

@lidel, do you mind having a look when it's convenient? Thank you!

[jessicaschilling]

Update: @lidel This takes care of all of the items on my current crib sheet related to the prefs page, so should be good for review whenever you have the chance (no hurry). I do request that you look at the changes to text to make sure I haven't introduced any inaccuracy 😊 Thanks!

[lidel]

Thank you for thorough review and fixes of all labels, really appreciate the time it took. 🙏

LGTM, I'm merging this, but will wait with release till next week, so IPFS Translation Team can apply tweaks in their locales, if needed.

[jessicaschilling]

@lidel thanks 😊 -- I've got some other Companion tweaks in the works, so we may want to wait to release anyway.