Fix overflow in bad token detection

[fedgiac]

We had some panics in prod because the NOT token uses maxuint256 for all user balances, which causes a panic when checking if the token is unsupported.

These changes fix the panic.

Test Plan

Updated ignored unit test:

$ cargo test -p shared mainnet_tokens -- --nocapture --ignored
[...]
token 0x0027449bf0887ca3e431d263ffdefb244d95b555 is Ok(Bad { reason: "token total supply does not fit a uint256" })
[...]

Also, compare the output of the test with its output on main to check that no other changes were introduced:

$ diff before after
104a105
> token 0x0027449bf0887ca3e431d263ffdefb244d95b555 is Ok(Bad { reason: "token total supply does not fit a uint256" })
107c108
< test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 250 filtered out; finished in 23.82s
---
> test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 250 filtered out; finished in 23.80s

[codecov-commenter]

Codecov Report

Merging #212 (314f00c) into main (aa29117) will decrease coverage by 0.00%.
The diff coverage is 46.66%.

@@            Coverage Diff             @@
##             main     #212      +/-   ##
==========================================
- Coverage   64.41%   64.40%   -0.01%     
==========================================
  Files         189      189              
  Lines       38788    38800      +12     
==========================================
+ Hits        24987    24991       +4     
- Misses      13801    13809       +8     

[MartinquaXD]

LGTM