fix: occasional ETXTBSY on CLI runs

[michelkaporin]

• Follows CONTRIBUTING rules

What does this PR do?

Customers see ETXTBSY error when running CLI on Linux systems.

This PR ensures that we resolve download function only upon close event, when both stream has finished and file descriptor is closed.

Executable doesn't exist, trying to download.
Downloading from 'https://static.snyk.io/cli/v1.1140.0/snyk-linux' to '/usr/local/lib/node_modules/snyk/wrapper_dist/snyk-linux'
...
Downloaded successfull!
{
  error: Error: spawnSync /usr/local/lib/node_modules/snyk/wrapper_dist/snyk-linux ETXTBSY
      at Object.spawnSync (internal/child_process.js:1107:20)
      at Object.spawnSync (child_process.js:776:24)
      at Object.runWrapper (/usr/local/lib/node_modules/snyk/wrapper_dist/common.js:142:33)
      at run (/usr/local/lib/node_modules/snyk/wrapper_dist/index.js:17:29)
      at /usr/local/lib/node_modules/snyk/wrapper_dist/index.js:34:26
      at runMicrotasks (<anonymous>)
      at processTicksAndRejections (internal/process/task_queues.js:95:5) {
    errno: -26,
    code: 'ETXTBSY',
    syscall: 'spawnSync /usr/local/lib/node_modules/snyk/wrapper_dist/snyk-linux',
    path: '/usr/local/lib/node_modules/snyk/wrapper_dist/snyk-linux',
    spawnargs: [ 'test', '--severity-threshold=low' ]

Failed to spawn child process. (/usr/local/lib/node_modules/snyk/wrapper_dist/snyk-linux)
�[31m✖ Running snyk test failed.�[0m

Where should the reviewer start?

How should this be manually tested?

Any background context you want to provide?

I didn't manage to write tests in a reasonable time, as the current download implementation couples the download using https and the piping logic very tightly, making it very hard to test this scenario.

What are the relevant tickets?

https://snyk.zendesk.com/agent/tickets/45267

Screenshots

Additional questions

[github-actions]

	Warnings
⚠️	Since the CLI is unifying on a standard and improved tooling, we're starting to migrate old-style imports and exports to ES6 ones. A file you've modified is using either module.exports or require(). If you can, please update them to ES6 import syntax and export syntax. Files found: ts-binary-wrapper/src/common.ts
⚠️	"fix: ensure that downloadExecutable doesn't resolve until file descriptor is closed" is too long. Keep the first line of your commit message under 72 characters.

Generated by 🚫 dangerJS against d96f196