Improved multi-project support for SAST Analyzers
With a git repo that contains multiple projects with the same language,
I would like for each of those projects to be scanned for security issues,
So that I can use the [monorepo](https://en.wikipedia.org/wiki/Monorepo) pattern while still gaining the benefit of GitLab's security scanners.
I think the main issue that would need to be solved would be to add support for finding multiple projects in https://gitlab.com/gitlab-org/security-products/analyzers/common
### Problem to solve
Improve support for scanning repos with multiple projects in the same language
### Intended users
* [Sasha (Software Developer)](https://about.gitlab.com/handbook/marketing/product-marketing/roles-personas/#sasha-software-developer)
### Further details
For certain languages we scan all applicable files; i.e. checking for the presence of `**/*.py`. Other languages instead rely on a special project file to detect the base directory and run the scan.
- `brakeman` looks for `application.rb` and scans location as first applicable project
- `spotbugs` does not support inheritance https://gitlab.com/gitlab-org/gitlab/-/issues/24076
### Proposal
A. Automatically scan all applicable projects within a repo *OR*
B. Provide improved documentation on how to configure scanners to scan distinct projects within a single repository
### Permissions and Security
No change to permissions
### What does success look like, and how can we measure that?
Better out-of-the-box scanning of monorepos
### What is the type of buyer?
gitlab~3207279
### Links / references
### Release notes
https://gitlab.com/gitlab-com/www-gitlab-com/-/merge_requests/70002
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