[FIX] ProjectBuilder now can be executed in parallel

[d3xter666]

Fixes: SAP/ui5-tooling#887

ProjectBuilder was using a singleton of the logger module. Basically, the logger was constructed only once, during module evaluation, but used throughout the whole module.
The tricky part is that the ProjectBuilder's logger has this setProjects() method that acts as an allow list of the projects being built. As the logger used to be a singleton within this module/class and the async behaviour of the whole module, calling setProject() was polluting the internal projects property.

With this fix, every ProjectBuilder instance has its ownBuildLogger instance that solves the issue.

[coveralls]

coverage: 95.955%. remained the same when pulling 3076e97 on fix-parallel-project-builder-exec into 052c20b on main.