Settings sections should be better ordered for popularity and complexity

[petemill]

Test plan

1. Visit brave://settings/
2. Ensure menu items are ordered (per below)
3. Ensure content area is ordered the same

Description

New order according to @bradleyrichter 👍

Getting started
Appearance
Sync
Shields
Social media blocking
Search engine
Extensions

[btlechowski]

Verification passed on

Brave	0.68.109 Chromium: 76.0.3809.62 (Official Build) dev (64-bit)
Revision	7b77856b3aa34d72f246d12340fc1ded8b2c0e83-refs/branch-heads/3809@{#798}
OS	Ubuntu 18.04 LTS

Used test plan from brave/brave-core#2530
Checked if all the links work as expected.

Verification passed on

Brave	0.68.114 Chromium: 76.0.3809.87 (Official Build) beta (64-bit)
Revision	111fe1e15d5ced26080a7dc239bcfe70f6c49aad-refs/branch-heads/3809@{#967}
OS	Windows 10 OS Version 1803 (Build 17134.523)

• Verified the test plan from Settings: Reorder sections brave-core#2530
• Verified all the links work as expected.
  

Verified passed with

Brave	0.68.114 Chromium: 76.0.3809.87 (Official Build) beta (64-bit)
Revision	111fe1e15d5ced26080a7dc239bcfe70f6c49aad-refs/branch-heads/3809@{#967}
OS	Mac OS X

• Verified the test plan from Settings: Reorder sections brave-core#2530
• Verified all the links work as expected.