[Discord] Properly support all URL variations

[beefchimi]

Discord has multiple different URL variations for different purposes:

1. User profiles (discordapp.com/users/*)
2. Server/channel urls (discord.com/channels/{serverid}/{channelid})
3. Official vanity urls (discord.gg/*)

Some examples of valid URLs:

• https://discord.com/users/username
• https://discordapp.com/users/0123456789
• https://discord.com/channels/@me
• https://discord.com/channels/892738558316662855
• https://discordapp.com/channels/serverid/channelid/messageid
• https://discord.gg/vanity-url

At the moment, Socialite works by simply parsing the domain to determine network type, and then parsing the path to determine handle. When parsing for handle, we do not use any other part of the full url to qualify the result.

Additionally, since Discord has different purposes for each of its URL structures... a single preferredUrl simply isn't compatible. Example: Parsing a channels URL and attempting to use the preferredUrl will lead no where useful.

There are two URL parts that may help us increase our confidence in the parsed handle + determine the ideal preferredUrl:

1. Domain: discord vs discordapp
2. Top-level domain: .gg vs anything else

It is also worth investigating the @ prefix to better understand its significance in Discord URLs. This may lead to yet another condition - or alternatively - provide an additional mechanism for gaining confidence over the result.

Since this PR, we introduce some snowflake code to handle the discord condition. We really need to pursue a higher-level solution to help solve for these cases.