feat: replace test lifecycle helpers with hooks

[schaable]

This PR replaces the direct helper calls that test runners make into the coverage and gas-analytics plugins with test hooks. This decouples the runners from those plugins and is preparatory work for combined gas statistics and support --json output for --gas-stats.

This follows the direction explored in #7568.

Summary

• Replace direct markTestRunStart/markTestWorkerDone/markTestRunDone helper calls with onTestRunStart/onTestWorkerDone/onTestRunDone test hooks
• Consolidate per-runner worker files (coverage.ts + gas-stats.ts) into a single test-worker-done.ts to avoid double-firing hooks when both features are enabled
• Remove hardhat/internal/coverage and hardhat/internal/gas-analytics export paths (no longer needed)

How it works

Before: Each test runner imported and called helpers from both plugins directly:

// v-next/hardhat/src/internal/builtin-plugins/solidity-test/task-action.ts
import {
  markTestRunStart as coverageMarkTestRunStart,
} from "../coverage/helpers.js";
import {
  markTestRunStart as gasAnalyticsMarkTestRunStart,
} from "../gas-analytics/helpers.js";

const runSolidityTests: NewTaskActionFunction<TestActionArguments> = async (
  { testFiles, chainType, grep, noCompile, verbosity },
  hre,
) => {
  await coverageMarkTestRunStart("solidity");
  await gasAnalyticsMarkTestRunStart("solidity");
  // code ...
}

After: Each test runner fires a single hook, and plugins respond via registered handlers:

// v-next/hardhat/src/internal/builtin-plugins/solidity-test/task-action.ts
const runSolidityTests: NewTaskActionFunction<TestActionArguments> = async (
  { testFiles, chainType, grep, noCompile, verbosity },
  hre,
) => {
  await hre.hooks.runSequentialHandlers("test", "onTestRunStart", ["solidity"]);
  // code ...
}

// v-next/hardhat/src/internal/builtin-plugins/gas-analytics/hook-handlers/test.ts
export default async (): Promise<Partial<TestHooks>> => ({
  onTestRunStart: async (context, id) => {
    // code ...
  },
}

// v-next/hardhat/src/internal/builtin-plugins/coverage/hook-handlers/test.ts
export default async (): Promise<Partial<TestHooks>> => ({
  onTestRunStart: async (context, id) => {
    // code ...
  },
}

Questions

• Do we have documentation that covers the hooks? Should we add docs for the test hooks?

[changeset-bot]

🦋 Changeset detected

Latest commit: 515c622

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
@nomicfoundation/hardhat-node-test-runner	Patch
@nomicfoundation/hardhat-mocha	Patch
hardhat	Patch

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[alcuadrado]

Let's change these to chained hooks, and always call next() first

[schaable]

Done in 9912d2a

[alcuadrado]

pre-approving