Display a warning when sending a token to its own address [Crypto Wallets]

[ryanml]

Currently, tokens can be freely sent to their own smart contract address with no warnings or stops. At the very least, a warning should be provided to users when attempting to make this transaction.

Test Plan

1. Initiate a send transaction.
2. Enter 0x0d8775f648430679a709e98d2b0cb6250d2887ef as the recipient (BAT Smart contract)
3. Select BAT as the asset to send

Actual Result

No warning displayed

Expected Result

Warning displayed

[srirambv]

Verification passed on

Brave	1.20.58 Chromium: 88.0.4315.7 (Official Build) nightly (x86_64)
Revision	9b020863b2987261f6dcd018c6b388041c035f98-refs/branch-heads/4315@{#15}
OS	macOS Version 10.15.7 (Build 19H114)
Component	1.0.19 Dev

• Verified warning message is shown when sending token to contract address
• 

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Verification passed on

Brave	1.19.74 Chromium: 87.0.4280.101 (Official Build) beta (64-bit)
Revision	9407c80213cda69c2b7abcb4fa8e3f74488f4956-refs/branch-heads/4280@{#1807}
OS	Linux
Component	1.0.19 Dev

• Verified warning message is shown when sending token to contract address
  

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Verification passed on

Brave	1.18.77 Chromium: 87.0.4280.101 (Official Build) (64-bit)
Revision	9407c80213cda69c2b7abcb4fa8e3f74488f4956-refs/branch-heads/4280@{#1807}
OS	Windows 10 OS Version 2009 (Build 19042.685)
Component	1.0.19 Dev

• Verified warning message is shown when sending token to contract address