cdxgen crash when scala project isn't at repository root dir

[rogeriobastos]

cdxgen crach when analyse a scala repository where the project dir isn't at the root directory. The following directory structure can be used to reproduce the bug.

/git/test/
└── src
    └── scala
        ├── build.sbt
        ├── project
        │   ├── build.properties

This is happening because determineSbtVersion() function is being called against the root dir here and it can't find the build.properties file. cdxgen crash with the following error:

Scanning /git/test/
Detected sbt version: null
/opt/node/lib/node_modules/@cyclonedx/cdxgen/node_modules/semver/classes/semver.js:19
      throw new TypeError(`Invalid version. Must be a string. Got type "${typeof version}".`)

With this PR if cdxgen can't detect sbt version at the root of repository being analysed it will loop over sbtProjects array trying to find a valid build.properties file.

[rogeriobastos]

I found an use case where this PR fails: when there are nested project directories and one build.properties does reference data on another. So I have to improve this fix.

[rogeriobastos]

I've rewrite the patch. I think it is ok now.

[prabhu]

Could you run npm run pretty?

[prabhu]

Thank you!