Cleanup showing sync & reward menu in app menu model

[simonhong]

Sync & Rewards are only valid in normal window.
They are valid In private window because they are redirected to normal window.
However, they doesn't work properly in tor(guest) window.
So, sync and rewards menu item should be visible only in normal & private window.
Also, corresponding commands should be disabled in tor(guest) window.

STR:
Case 1)

1. Open private window and click app menu button
2. Check rewards & sync menu are visible
   (Current status is sync is hidden)

Case 2)

1. Open tor window and click app menu button
2. Check rewards & sync menu are hidden
   (Current status is rewards is visible)

[btlechowski]

Verification passed on

Brave	0.63.4 Chromium: 73.0.3683.67 (Official Build) dev (64-bit)
Revision	a83fd4f3207ae83412d329a9ca1239dd1e068345-refs/branch-heads/3683@{#760}
OS	Windows 7 Service Pack 1 Build 7601.24312

Used test plan from the description

tor window

guest window

private window

Verified passed with

Brave	0.63.14 Chromium: 73.0.3683.75 (Official Build) dev(64-bit)
Revision	909ee014fcea6828f9a610e6716145bc0b3ebf4a-refs/branch-heads/3683@{#803}
OS	Mac OS X

• Verified Test Plan from description
  Normal Window
  

Private Window

Tor Window

Guest Window

Verification passed on

Brave	0.63.14 Chromium: 73.0.3683.75 (Official Build) dev(64-bit)
Revision	909ee014fcea6828f9a610e6716145bc0b3ebf4a-refs/branch-heads/3683@{#803}
OS	Ubuntu 18.04 LTS

Used test plan from the description