Added preBuildScript to add custom script just before running the build #214
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
TODO: Check the above box with an 'x' indicating you've read and followed CONTRIBUTING.md.
What does this Pull Request accomplish?
Adds a preBuildScript that can be used to run custom script before build.
Why should this Pull Request be merged?
It will help other custom devices which uses the template "stages.yml" to get a feature of running their own script before build.
What testing has been done?
Using PR Build

Used the "preBuildScript" step feature in the azure-pipelines.yml of this repo to test
Running code successfully:
Running before build:
