[deployment] Introduce deployment steps [5.3.0-B1]

Currently the deployment process consists of 2 steps, that are executed one after another on each deployment:

1. svn update
2. upgrade database + import language pack (both done for each module)
3. resetting various caches + discovering changes in theme files (happens once)

That scheme works pretty fine, when deployment happens on one machine only. When there are several Web Servers in application layer (all using same database) and deployment needs to be made on each of them, then we need to do this instead:

1. On master machine:
   1. svn update
   2. upgrade database + import language pack (both done for each module)
2. On each machine (except master):
   1. svn update
3. On master machine:
   1. resetting various caches + discovering changes in theme files (happens once)

Solution

To make this possible the adm:OnDeploy event needs to be thought to run deployment on step-basis (you tell which steps to run, when needed).

Related Tasks

INP-1391 - Getting issue details... STATUS