Consider setting projectPath based on .git directory if one exists

[danielbachhuber]

If I run wp-now start anywhere from a git clone, I may want it to reuse the same WordPress instance.

We could consider looking upwards for a .git directory, and use that as the projectPath if it exists.

From #39 (comment)
Related #26

[lemanschik]

while i like the pattern to search for a .git directory this does not scale well we need a
wp-now.config.json inside the project directory or alternative for vscode inside the .vscode project folder.

The most standard scenario is the one where we even need more then a single wp-now deployment to migrate data and settings and maybe even work with a directory that has many wp installations.