Allow the end user to move/reposition custom ad notifications

[tmancey]

No description provided.

[tmancey]

Resolved as part of #13132, please test as part of the new custom ad notifications

[btlechowski]

Verification passed on

Brave	1.26.50 Chromium: 91.0.4472.77 (Official Build) beta (64-bit)
Revision	1cecd5c8a856bc2a5adda436e7b84d8d21b339b6-refs/branch-heads/4472@{#1246}
OS	Ubuntu 18.04 LTS

Verified able to move the custom ad notification

Verified the position is retained for the next ad, even after browser restart

Verified the custom ad notification respects System UI

Verified the custom ad notification responds to System UI changes

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Verified PASSED using

Brave	1.26.50 Chromium: 91.0.4472.77 (Official Build) beta (x86_64)
Revision	1cecd5c8a856bc2a5adda436e7b84d8d21b339b6-refs/branch-heads/4472@{#1246}
OS	macOS Version 11.4 (Build 20F71)

Verified able to move the custom ad notification

Verified the position is retained for the next ad, even after browser restart

Verified the custom ad notification respects System UI

Verified the custom ad notification responds to System UI changes

---

Verification passed on

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Brave | 1.26.50 Chromium: 91.0.4472.77&nbsp;(Official Build)&nbsp;beta&nbsp;(64-bit)
-- | --
Revision | 1cecd5c8a856bc2a5adda436e7b84d8d21b339b6-refs/branch-heads/4472@{#1246}
OS | Windows&nbsp;10 OS Version 2004 (Build 19041.985)

<!--EndFragment-->

• Verified that the custom Ad notifications can be reposition
• Custom Ad notification popup size is enlarged after reposition. Logged a follow-up issue Follow up of #14813 - The size of the custom ad notification popup is enlarged after reposition #16241