[Feature] Register a new submarine

[SnowHawkeye]

Description

Implement the ability to add a new submarine with /register. For now, a ship is registered server-wise.
When using the command, a message appears with the following message components:

• type (string select, but for now only "submarine" should be available)
• name of the ship (text input)
• rank (text input, but must make sure it's an integer)
• build (series of 4 string selects with the possible parts)
• channel (the discord channel where ship notifications will be sent)
• a button to submit the form

Acceptance criteria

• When using the command, an ephemeral message as described above appears
• When submitting the form, all the above information is committed to storage
• Relevant documentation has been added