[build-system] Move scripts from `build/` to `scripts/`

Description

It is bad practice to version control a directory named build. Often times IDEs will default to using that folder as their build directory and as a result it can fail to configure. A few scripts were moved out of the build directory in the past, and this commit finishes this transition.

Note that this MR requires some changes in the buildbot configuration (e.g. here). Will update with the dependent MR here (MR are disabled there).

Checklist

• I have checked that my code follows the Octopus coding standards
• I have added tests for all the new features added in this request.