Move build stage to a dedicated worker that could be reused later

Currently being worked on here . #2675

Fix executor HTTP API to be REST compatible with proper usage of HTTP CRUD methods and entities as endpoint names.

For the executor, I'm thinking of the following structure

Execute a function
POST /v1/executor/functions/:functionId

Delete a function
DELETE /v1/executor/functions/:functionId

Delete a tag
DELETE /v1/executor/functions/:functionId/tags/:tagId

Create Runtime Server
POST /v1/executor/functions/:functionId/tags/:tagId/runtime

Re-trigger a build
POST /v1/executor/tag/:tagId/builds/:buildId

Double check new indexes and if we miss any

Will Do ✅

When we delete a tag we should delete all builds

@eldadfux in the current structure, a build does not store the tagID it's associated with. We need to add a new tagId attribute for the builds collection so we're able to find all the associated builds for a tag easier.

Should all v1/functions/builds be nested under /v1/functions/:id/tags/:id/builds or just under /v1/functions/:id?

I personally prefer /v1/functions/:id/tags/:id/builds
In this case again, we still need to add a tagId attribute to each build so we're able to fetch them easily.

Fixed all the conflicts with the target branch, tests pass locally 👍🏻