Add tools to support localization and emoji management.

[ShindouMihou]

As slash commands are coming to support localization, I think it's safe to say that Nexus should also support some sort of tooling to easily integrate JSON-based i18n localization with placeholders and custom emoji support to make development easier.

A sample JSON example would be (en.json):

{
   "hello": "world"
}

which translates into the resource name hello that can be retrieved with the following method (Kotlin):

val nexus: Nexus = ...
val hello: String = nexus.internalization["en"]["hello"]

It should support nested objects by moving them into namespaces such as:

{
  "hello": {
     "world": "Hello World"
   }
}

which translates into the resource name hello.world that can be retrieved with the following method (Kotlin):

val nexus: Nexus = ...
val hello: String = nexus.internalization["en"]["hello.world"]

Emoji placeholder should also be supported with the following example:

val nexus: Nexus = ...
nexus.emojis["iara_wow"] = 863994252329353237L 

val hello: String = nexus.internalization["en"]["hello.world"]

{
  "hello": {
     "world": "Hello World :[iara_wow]:"
   }
}

It would then read the file and notice the emoji placeholder and map it to the iara_wow emoji immediately to save performance costs which results in the following value:

Hello World <:iara_wow:863994252329353237>

Mapping named placeholders would also function similarly but are translated in real-time instead with an example being:

{
  "hello": {
     "world": "Hello World <[user]>"
   }
}

val nexus: Nexus = ...

// imagine this is inside a command function with an event
val helloMapper: NexusMapper = nexus.internalization["en"].mapper["hello.world"]

helloMapper.set("user", { event.user.name })

val hello: String = helloMapper.toString()

[ShindouMihou]

As a step-up to this idea, I think it's better to do this in a more unopinionated manner such as how we are enforcing JSON. A better proposal to this would be allowing a configuration that'll allow us to read the internalization files:

Nexus.configure {
    internalization.collector = (lang: String) -> ...
}

This will allow us to configure how are collecting all the contents that we need, it is now up to the developer how they want to set-up the naming scheme whether they want to use a dot-separated naming scheme or another since all that Nexus needs a key-value.
internalization.collector: (lang) -> Map<String, String>