ENS confusables should not include the regular letter "m"

[serenae-fansubs]

Describe the bug
When an ENS name is entered and contains the letter "m", Metamask flags this (incorrectly in my opinion) as a confusable character. This also appears to happen to the digits "0" and "1".

Screenshots

To Reproduce
Enter any ENS name that contains "m", like temp.eth
Enter any ENS name that contains "0", like 0xbitcoin.eth
Enter any ENS name that contains "1", like 1bitcoin.eth

Expected behavior
Metamask should not display that "potential scam" warning when the name just has a letter m in it

In general, if a name is only comprised of "regular" characters [a-z0-9], the confusable warning message should not appear.

[serenae-fansubs]

I see that this was pointed out in multiple places on the original feature, but was dismissed as "not a bug":

#2464 (comment)

[serenae-fansubs]

The same thing appears to happen for the digits "0" and 1" too. Maybe other characters too.

In general, the "confusable" message should not be shown for any character [a-z0-9].

[rickycodes]

hi @serenae-fansubs

m, 0 and 1 are all valid confusables. the library we're using to flag these is just pulling from a standard document: http://www.unicode.org/reports/tr39/.

here's the full list: https://unicode.org/Public/security/10.0.0/confusables.txt, you can see the m -> rn case. m gets flagged here because it's similar to rn.

for the 0 & 1 cases the mapping is:

"0": "O",
 "1": "l",

because 0 can be confused with O and 1 can be confused with l.

The extension does something similar:

I've opened #3902 in a effort to better explain why characters get flagged in ENS names (similar to what extension does). I hope this helps.