New Tab Page: move components from brave-ui to brave-core

[petemill]

The NTP components are specific to brave-core. It will be more productive to have these inside the brave-core repo rather than in a separate repo (brave-ui).

Reasoning and steps explained in #2335

Test Plan

NTP works

• Open NTP
• Check renders and no console errors

[LaurenWags]

Verified passed with

Brave	0.69.114 Chromium: 76.0.3809.100 (Official Build) beta (64-bit)
Revision	ed9d447d30203dc5069e540f05079e493fc1c132-refs/branch-heads/3809@{#990}
OS	Mac OS X

• Verified test plan from description

Verification passed on

Brave	0.69.116 Chromium: 76.0.3809.100 (Official Build) beta (64-bit)
Revision	ed9d447d30203dc5069e540f05079e493fc1c132-refs/branch-heads/3809@{#990}
OS	Ubuntu 18.04 LTS

• Verified test plan from the description

Verification passed on

Brave	0.69.113 Chromium: 76.0.3809.100 (Official Build) beta (64-bit)
Revision	ed9d447d30203dc5069e540f05079e493fc1c132-refs/branch-heads/3809@{#990}
OS	Windows 10 OS Version 1803 (Build 17134.523)

• Verified test plan from the description