l10n: revise and update zh_TW translation

[kisaragi-hiu]

The main thing is addressing vocabulary that are unnatural in zh_TW (eg. 當前 is as zh_CN as color is en_US), but I also made some revisions for grammar and translated everything that hasn't been translated yet.

Translate

• Address Bar

  Using 網址列 for Address Bar because that's what Firefox zh_TW uses.

• Sticky ancestor tab strings

  "sticky" as in "if it would scroll off keep it at the top instead" is not in zh (or even really anywhere except English), so I had to just expand out the definition (固定於上方顯示, "keep it displayed on top").

• Everything else

Revise

• Use '不切換' for settings.scroll_through_tabs_none.

  A single 不 is very unnatural. This is like settings.switch_panel_after_switching_tab_no, where it's necessary to repeat what action we don't do to make it grammatical.

• Fix 快照 being used as a counting word (settings.snap_limit_snap)

  In the snapshot limit, "snapshots" is used for a count of snapshots (like "10 snapshots"), but "10 快照" is not valid zh_TW or zh_CN.

  I chose to use 快照數 instead of ...個快照 since this string is also doubling as an option for what limit mode to use. "個快照" does not sound like a limit mode.

• Use "Proxy 設定", not just 代理, for Proxy

  The issue with 代理 alone is that it is ambiguous with Agent (代理程式 in full, often also shortened to 代理). (I'm not sure if this issue exists in zh_CN, which is why I only added a zh_TW translation.)

  Firefox zh_TW uses both 代理伺服器 and "Proxy", with "Proxy" being the one that's used more primarily (like "手動設定 Proxy" or "使用系統 Proxy"), so I chose Proxy over 代理伺服器.

• zh_TW 禁用 means Prohibit, not Disable. Disable is 停用 in zh_TW

• Fix 字符串 in "substring or /RegExp/"

  字符串 is not in zh_TW. It's as jarring in zh_TW as saying a lift instead of an elevator in en_US.

  I localized the quotes to hopefully make it more clear they don't go into the rule (double quotes are literal in the field, "github" with quotes matches URLs that also contain the quotes).

• 當前 -> 目前

  The zh_TW word for "current" is 目前; "當前" is as jarring as "colour" would be in en_US.

  Because 非目前的 is not a word, I replaced it with the next best thing, "非作用中的".

• 折疊 -> 摺疊

  zh_TW has 3 valid translations for "collapse" (collapsing a previously expanded thing): 收起, 折疊, and 摺疊.

  折疊 is fine, but Firefox zh_TW mainly uses 摺疊.

  Searching on firefox-l10n: 摺疊 has 19 matches; 折疊 has 2 matches, both seem like consistency mistakes; 收起 has 3 matches but they are from accessibility properties for 3 platforms so it's really more like 1 match.