Add base64 & hex decoding to @lune/serde

[Hexcede]

Lune does not currently provide a way to do base64 or hexadecimal encoding/decoding. Both of these would be extremely useful when interacting with various APIs over HTTP.

[CompeyDev]

Hex encoding and decoding can already be done in Luau, unless I am misunderstanding you.

-- Encode
local encoded = string.format("%x", int)

-- Decode
local decoded = tonumber(encoded, 16)

[Hexcede]

Hex encoding and decoding can already be done in Luau, unless I am misunderstanding you.

-- Encode
local encoded = string.format("%x", int)

-- Decode
local decoded = tonumber(encoded, 16)

You can implement hex encoding/decoding in pure lua/luau, but, you can also do the same for JSON, TOML, Base64, etc, to varying ease of implementations. Having these as part of serde is a lot more of a QoL and performance interest than a necessity.

[CompeyDev]

You should specify that you want support for hex and base64 encoding for serializing data. The current issue is a bit vague and comes off as general support for them.