p-token: Add scripts

[febo]

Problem

Currently it is not possible to build and test p-token program using pnpm scripts.

Solution

Add p-token:build and p-token:test to package.json to build and test the program.

Starting from a fresh clone:

pnpm install

to install pnpm dependencies. Then we can use:

pnpm p-token:build

to build p-token binary – it will be located at ./target/deploy/pinocchio_token_program.so. You can also use:

pnpm p-token:test

to run p-token tests.

[joncinque]

All of the renames probably belong in #24, but no big deal, it'll all land anyway, looks good!