Enable the user to add arbitrary strings to the agent's masque

[mssalvatore]

Description

The web UI must enable users to set the agent's masque (see #3241). The simplest thing would be to provide string fields to users (similar to how users specify IP addresses in network configuration). The UI would transform the strings to bytes and separate them with null characters (0x00).

Notes:

On UI load:
    call GET /api/agent-binaries/{linux,windows}/masque and populate the tab
On submit:
    if detection data is set:
        call SET /api/agent-binaries/{linux,windows}/masque=masque
    else:
        call SET /api/agent-binaries/{linux,windows}/masque = None

On export:
    Add a new export section for masques and put the data in it.

On import:
    If the masque section has data:
        call SET /api/agent-binaries/{linux,windows}/masque = masque
    else if data section is empty or missing:
        call SET /api/agent-binaries/{linux,windows}/masque = None

Tasks

• Add the necessary fields to the UISchema (0d) @ilija-lazoroski
• Populate the field/data from the Island on config UI load (0d) @ilija-lazoroski
• On submit (0d) @ilija-lazoroski
  • strip the masque fields from the UI schema
  • call the appropriate endpoint(s) with the masque data
• Implement export (0d) @ilija-lazoroski
• Implement import (0.25d) @ilija-lazoroski
• Update documentation (0d) @mssalvatore
• Rename get() -> getJson() and getRaw() -> get() @ilija-lazoroski