core[minor]: Add graph functionality to Runnable base

[albertpurnama]

Description

• Adds Graph class port over from Python's Graph implementation here
• Adds getGraph to base Runnable to allow constructing graph representation of the Runnable. This should be exact port of this function in python

Failing test case

(Use `node --trace-warnings ...` to show where the warning was created)
@langchain/core:test: FAIL src/runnables/tests/runnable_graph.test.ts
@langchain/core:test:   ● Test graph sequence
@langchain/core:test: 
@langchain/core:test:     expect(received).toBe(expected) // Object.is equality
@langchain/core:test: 
@langchain/core:test:     - Expected  - 18
@langchain/core:test:     + Received  +  2
@langchain/core:test: 
@langchain/core:test:     @@ -17,20 +17,11 @@
@langchain/core:test:             "target": 3,
@langchain/core:test:           },
@langchain/core:test:         ],
@langchain/core:test:         "nodes": Array [
@langchain/core:test:           Object {
@langchain/core:test:     -       "data": Object {
@langchain/core:test:     -         "properties": Object {
@langchain/core:test:     -           "name": Object {
@langchain/core:test:     -             "title": "Name",
@langchain/core:test:     -             "type": "string",
@langchain/core:test:     -           },
@langchain/core:test:     -         },
@langchain/core:test:     -         "title": "PromptInput",
@langchain/core:test:     -         "type": "object",
@langchain/core:test:     -       },
@langchain/core:test:     +       "data": Object {},
@langchain/core:test:             "id": 0,
@langchain/core:test:             "type": "schema",
@langchain/core:test:           },
@langchain/core:test:           Object {
@langchain/core:test:             "data": Object {
@langchain/core:test:     @@ -49,11 +40,10 @@
@langchain/core:test:             "data": Object {
@langchain/core:test:               "id": Array [
@langchain/core:test:                 "langchain",
@langchain/core:test:                 "llms",
@langchain/core:test:                 "fake",
@langchain/core:test:     -           "llm",
@langchain/core:test:                 "FakeLLM",
@langchain/core:test:               ],
@langchain/core:test:               "name": "FakeLLM",
@langchain/core:test:             },
@langchain/core:test:             "id": 2,
@langchain/core:test:     @@ -71,17 +61,11 @@
@langchain/core:test:             },
@langchain/core:test:             "id": 3,
@langchain/core:test:             "type": "runnable",
@langchain/core:test:           },
@langchain/core:test:           Object {
@langchain/core:test:     -       "data": Object {
@langchain/core:test:     -         "items": Object {
@langchain/core:test:     -           "type": "string",
@langchain/core:test:     -         },
@langchain/core:test:     -         "title": "CommaSeparatedListOutputParserOutput",
@langchain/core:test:     -         "type": "array",
@langchain/core:test:     -       },
@langchain/core:test:     +       "data": Object {},
@langchain/core:test:             "id": 4,
@langchain/core:test:             "type": "schema",
@langchain/core:test:           },
@langchain/core:test:         ],
@langchain/core:test:       }
@langchain/core:test: 
@langchain/core:test:       33 |   // expect(Object.keys(graph.nodes).length).toBe(5);
@langchain/core:test:       34 |
@langchain/core:test:     > 35 |   expect(graph.toJson()).toBe({
@langchain/core:test:          |                          ^
@langchain/core:test:       36 |     nodes: [
@langchain/core:test:       37 |       {
@langchain/core:test:       38 |         id: 0,
@langchain/core:test: 
@langchain/core:test:       at Object.toBe (src/runnables/tests/runnable_graph.test.ts:35:26)
@langchain/core:test: 

This is because the implementation of base Runnable is still TBD. Specifically here (same for the last node)

The solution to this requires the base Runnable to be fully implemented

Fixes #4582

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[albertpurnama]

@jacoblee93 Here's where I'm a little bit lost,

I'm trying to find a way to put the schema of the input node of this runnable. I haven't been able to find it yet.

This should be similar to get_input_schema in Python's core lib.

I think for graphing purposes, we might be able to replace this with a placeholder and maybe implement this later when we're going to use Zod.

[albertpurnama]

Same case as the above.

[nfcampos]

we prob want to type this

[nfcampos]

I think we want to use node.data.getName() here

[jacoblee93]

Hey sorry about the delay - will spend some time with this tomorrow and hopefully ship it!

[jacoblee93]

Wouldn't be any reason to preemptively make this async right?

[jacoblee93]

I will land @albertpurnama, thank you for this!

[jacoblee93]

Thank you very much for your patience and the great work @albertpurnama!