Missing progress spinner on "Use local node" button for full-page IPFS explainer

[stephendonner]

Description

Missing progress spinner when installing/initializing local IPFS node; see #13655

Steps to Reproduce

1. new profile
2. load ipfs://bafybeiemxf5abjwjbikoz4mc3a3dla6ual3jsgpdr4cjr3oz3evfyavhwq/wiki/Vincent_van_Gogh.html
3. on the resulting IPFS explainer page, click on "Use local node"
4. look for a (missing) progress spinner to the left of the button text

Actual result:

Expected result:

Progress/working spinner appears to the left of the "Installing..." text on the button

Reproduces how often:

100%

Brave version (brave://version info)

Brave	1.23.2 Chromium: 89.0.4389.58 (Official Build) nightly (x86_64)
Revision	1a139f28ecc27719439e37c6b1533cee999cb802-refs/branch-heads/4389@{#1134}
OS	macOS Version 11.2.1 (Build 20D74)

Version/Channel Information:

• Can you reproduce this issue with the current release? no
• Can you reproduce this issue with the beta channel? no
• Can you reproduce this issue with the nightly channel? yes

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields?
• Does the issue resolve itself when disabling Brave Rewards?
• Is the issue reproducible on the latest version of Chrome?

Miscellaneous Information:

cc @bbondy @karenkliu

[karenkliu]

Need to use the button component here: https://www.figma.com/file/z9wmg2FCwuXx9FLbDo5avJ/Platform-UI-Brave-desktop?node-id=1011%3A0
cc @petemill or @AlanBreck