feat(js): added abort signal to actions/flows

[pavelgj]

Fixes #3023

const testFlow = ai.defineFlow(
  { name: 'testFlow' },
  async (input, { abortSignal }) => {
    if (abortSignal.aborted) return; // ABORT
    abortSignal.onabort = () => {
      // ABORT: abortSignal.reason
    };
  }
);
const ctrl = new AbortController();
const responsePromise = testFlow('foo', {
  abortSignal: ctrl.signal,
});
ctrl.abort('reason');

Checklist (if applicable):

• PR title is following https://www.conventionalcommits.org/en/v1.0.0/
• Tested (manually, unit tested, etc.)
• Docs updated (updated docs or a docs bug required)

[ssbushi]

Quick LGTM

[zerolethanh]

@pavelgj If I send a abortSignal from client (like web or app) as describe here (https://developer.mozilla.org/en-US/docs/Web/API/AbortSignal), this abort function might working?