* core: keep whitelisted query parameters when removing link tracking
In safe mode, "remove link tracking" stripped any query parameter whose
name started with a known tracking prefix in qsSafeBlacklist, ignoring
qsWhitelist. So "list" (e.g. YouTube playlist links) was dropped because
"li" (LinkedIn) is a prefix of it, and github's "ref" was dropped too.
Make the safe-mode filter consult the whitelist, like the other branches.
* docs: plan for keeping whitelisted query parameters when removing link tracking
Design doc for the safe-mode sanitizeUri change (PR #6965): why "?list=" was
stripped from YouTube links, the root cause (safe mode ignoring qsWhitelist),
the fix, what it does/doesn't change, and alternatives considered.
Narasimha-sc
eb4f601c8b