A microVM id and its generator.

An id is a v prefix followed by lowercase base32 of 10 random bytes, charset [a-z2-7] - alphanumeric only, no -, _, or other punctuation. That charset is the intersection of three independent constraints the id must satisfy at once:

• firecracker rejects _ in an instance id (InvalidInstanceId);
• dm/jailer names must not start with -;
• registry keys and chroot path components stay trivially safe.