Create a library for commonly-used shapes

We operate on all kinds of RDF data. Most of that can be consistently described using shapes. Defining Shex Shapes will be the first step on the way to improve data integrity and type safety. Using the shex shapes, we can validate incoming data which improves security and stability.

For [LDO](https://ldo.js.org/) types and data validation it will be necessary to define common shapes for the data we use.

For ActivityPub there are shapes defined already: https://github.com/p2p-ld/linkml-activitypub/tree/main/generated/shex
We might use the same library as used in the AP repository above, to describe other shapes, since we can translate into various schema formats this way.

By bundling everything as a package, others can benefit from it too.

The issue does not name any repository files, tests, or entry points. Start by reviewing the ActivityPub Shex examples in the linked generated/shex directory and the existing package structure, then determine which common RDF shapes and schema-generation approach belong in a reusable package. Done means the package contains agreed common shapes and supports the intended validation or schema translation use cases.

Written by the indexing model from the issue text.