[EPIC] New v0 metadata structure

[Zorlin]

This lays out a metadata structure we're going to call v0.

Tests are required for each and every task, even if they're super basic tests; just want to make sure we're not breaking these functions as we go

Support creating:

• Function to create root document #2
• Function to create a directory document #3
• Function to create children document #4
• Function to create a file document #5
• Blob creation function #6

Support modifying/replacing:

• Modify root document #7
• Modify directory document #8
• Modify children document #9
• Modify file document #10
• Replace blob with different blob #11

Support moving:

• Allow moving directory #12
• Allow moving file #13

Overall design - https://github.com/user-attachments/assets/a2bdfa31-5c4a-4637-96fd-be1e687280d0

Root document

The root document will simply be a document that looks like this:

Key	Value	Description
type	"root"	Root document type
directory	documentID	Document with root directory documentID

Directory document

The directory document will simply be a document that looks like this:

Key	Value	Description
type	"directory"	Directory document type
children	documentID	Document with children list document
name	string	Name of directory (without paths)
metadata	documentID	Document with metadata associated with this directory

Children document

Key	Value	Description
type	"children"	Children document type
fsdir-movies	documentID	Link to a directory document with "movies" dir in it
fsfile-RiP - A Remix Manifesto.mkv	documentID	Link to a file document with "RiP - A Remix Manifesto.mkv" file in it
metadata	documentID	Document with metadata associated with this directory

File document

Key	Value	Description
type	"file"	File document type
name	string	Name of file (without paths)
blob	blobID	Link to a blob with "RiP - A Remix Manifesto.mkv" file in it
metadata	documentID	Document with metadata associated with this directory

Blob document

<No format specified, it's just a plain Iroh blob>