WebTorrent: Rename "Save File" button to make functionality clearer

[feross]

Description

When clicking on a .torrent file, the button "Save File" that appears implies to me that the torrent's contents can be saved by clicking it. In fact, this button downloads the .torrent file.

I recommend naming this "Save .torrent File" instead. Feedback from the design team is welcome.

Steps to Reproduce

1. Visit https://webtorrent.io/free-torrents
2. Click Big Buck Bunny (torrent file)
3. Start downloading torrent
4. Look at the "Save File" button

Actual result:

Expected result:

"Save .torrent File"

Reproduces how often:

Easily reproduced

Brave version (brave://version info)

Version 0.66.101 Chromium: 75.0.3770.142 (Official Build) (64-bit)

Version/Channel Information:

• Can you reproduce this issue with the current release? Yes
• Can you reproduce this issue with the beta channel? Yes
• Can you reproduce this issue with the dev channel? Yes
• Can you reproduce this issue with the nightly channel? Yes

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields? No
• Does the issue resolve itself when disabling Brave Rewards? No
• Is the issue reproducible on the latest version of Chrome? N/A

Miscellaneous Information:

[rebron]

cc: @rossmoody

[feross]

@rossmoody's mocks for the redesign we're discussing in #5402 and on Slack in #webtorrent use this new copy, so let's go ahead with it.

[btlechowski]

Verification passed on

Brave	0.70.96 Chromium: 76.0.3809.132 (Official Build) beta (64-bit)
Revision	fd1acc410994a7a68ac25bc77513d443f3130860-refs/branch-heads/3809@{#1035}
OS	Ubuntu 18.04 LTS

• Verified test plan from WebTorrent: Rename "Save File" to "Save .torrent File" brave-core#3036

During downloading

Downloading is finished

Verification passed on

Brave	0.70.97 Chromium: 77.0.3865.65 (Official Build) beta (64-bit)
Revision	87a331a3169cab563505fb44011058b904011ba1-refs/branch-heads/3865@{#726}
OS	Windows 10 OS Version 1803 (Build 17134.1006)

• Verified test plan from WebTorrent: Rename "Save File" to "Save .torrent File" brave-core#3036
  

Verification PASSED on macOS 10.14.6 x64 using the following build:

Brave	0.69.126 Chromium: 77.0.3865.65 (Official Build) (64-bit)
Revision	87a331a3169cab563505fb44011058b904011ba1-refs/branch-heads/3865@{#726}
OS	macOS Version 10.14.6 (Build 18G95)