ocibundle: confusing naming for tools.<type>.Path code

[dtrudg]

Type of issue

technical debt

Description of issue

In ocibundle.tools there is a pattern like:

type Rootfs string

func (r Rootfs) Path()

Where the value of the Rootfs string itself is the bundle path, and Rootfs.Path() gives the rootfs path inside that bundle.

This is very confusing from the point of view of type naming etc.

At point of use it is slightly better... Rootfs("mybundle").Path() being possible to read as give me Path of the Rootfs of "mybundle".

We should consider deprecating and replacing with nicer named functions on a single bundle type / struct.