[FEATURE] Add custom hook support

[joluj]

User Story

1. As a {developer that uses the Jayvee lib}
2. I want {to add custom hooks that run before or after blocks}
3. So that {I can enrich Jayvee without modifying the original source code}

User Acceptance Criteria

• Users of the Jayvee lib can add hooks to all blocks
• Users of the Jayvee lib can add hooks to individual blocks (not in the first version)
• Users of the Jayvee lib can add hooks to whole pipelines / programs (not in the first version)
• The number of hooks per blocks is not limited

A hook is basically a function that is called when due.

• It can be blocking or non-blocking. It's a user's choice. Default: non-blocking
• It can be asynchronous (important detail for blocking functions).
• If it's a pre-block hook: It retrieves the input parameters of a block (i.e. metadata and data).
• If it's a post-block hook: It retrieves the input and output parameters of a block (i.e. metadata and input data and output data).
• In this first version, there is no option to alter the input or output data or metadata.

Examples

I can imaging that we can use it like that:

const myJayveeProgram = // ...;
myJayveeProgram.addPreBlockHook(async ({args, input}) => {
  console.log(args); // type `unknown`? For now at least
  console.log(input); // type `unknown`? For now at least
}, {
  blocking: true,
});

myJayveeProgram.execute();

Notes

No support is needed for:

• Removing hooks

Definitions of Done

• A PR has been opened and accepted
• All user acceptance criteria are met
• All tests are passing

[joluj]

@TungstnBallon This is a first version for the hooks. There is not much options available for this first draft of the hooks, more advanced feature will come in follow up issues.