Adding NFT doesn't work the first time

[srirambv]

Description

Adding NFT doesn't work the first time

Steps to Reproduce

1. Try adding a NFT
2. Sometimes doesn't work the first time

Actual result:

Adding NFT doesn't work the first time. Couple of retry or giving it a few mins and trying again works

Expected result:

Should be able to add NFT's instantly (whether you own it or not)

Reproduces how often:

Easy

Brave version (brave://version info)

Brave	1.44.97 Chromium: 106.0.5249.55 (Official Build) (64-bit)
Revision	4d5f098fca6ab7f4b6b7c240be3d9593c2357709-refs/branch-heads/5249@{#531}
OS	All

Version/Channel Information:

• Can you reproduce this issue with the current release? NA
• Can you reproduce this issue with the beta channel? Yes
• Can you reproduce this issue with the nightly channel? Yes

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields? NA
• Does the issue resolve itself when disabling Brave Rewards? NA
• Is the issue reproducible on the latest version of Chrome? NA

Miscellaneous Information:

cc: @muliswilliam @nvonpentz

[muliswilliam]

@srirambv I separated the NFT form from the general add custom asset form. I have tested the new implementation in latest master and it is okay.