Use esbuild lib instead of npx

[chalosalvador]

Description

Scenarios Tested

Sample Commands

[leoortizz]

@jamesdaniels this would address #7250 and #6193, WDYT?

[jamesdaniels]

We use to do this. The trouble here is that firebase-tools pins dependencies. So we were pinning to a version of esbuild that was not supported on customer's machines, be it node version or architecture.

Perhaps we could be smart and do some equivalent of "npm install" and "npm which"