An IPLD Path is a string identifier used for deep references into IPLD graphs.
IPLD Path's are constructed following the same constraints as URI Paths.
Similarly, the string ? is reserved for future use as a query separator.
Path resolution is broken into two parts: full path resolution and block level resolution.
Block level path resolution is defined by individual codecs.
Full path resolution should use block level resolution through each block.
When a block level resolver returns an IPLD Link a full path resolution
should retreive that block, load its codec, and continue on with additional
block level resolution until the full path is resolved. Finally, path resolution
should return a representation
of the value for the given path.