Fix dev server run error when path contains spaces

[thedavidprice]

Related #596

This addresses two separate problems when paths contain spaces:

1. errors when checking if dir or file exists: the previous implementation gave a false-negative if the path contained a space
2. running the commands with concurrently: running commands will fail if the path spaces are not sanitized

Solutions:

• for dir and file validation checks, uses getPaths()
• in case of DB, now checks if schema.prisma exists
• in case of effectively setting the working directory for concurrently (e.g. cd api/), we still need to use the "sanitize-path" method replace(' ', '\\ '), otherwise spaces still cause the run(s) to fail

[thedavidprice]

@peterp I've been testing on Windows Powershell. And I'm getting some strange behavior for paths using getPaths(), both with and without spaces, specifically:

• getPaths().api.base returns undefinded
• getPaths().web.base returns undefinded
  ...BUT...
• getPaths().api.dbSchema returns successfully (with or without space) as well as
• getPaths().web.srcreturns successfully
• getPaths().api.srcreturns successfully

So, more ¯_(ツ)_/¯

[thedavidprice]

Last change --> added " to the bash cd command to support both Windows and Mac in case of space in path.

@peterp Per my tests, this is working on both Windows and Mac with/without spaces in paths. I would appreciate your eyes on this before merging. It's a messy one.

[peterp]

Looks good to me!

[thedavidprice]

@peterp Cool, I'll merge now.

Just want to make sure I (re)highlight this strange behavior on Windows Powershell 'cause it might come back to bite us:

• getPaths().api.base returns undefined
• getPaths().web.base returns undefined

I'm about to test something similar on build.js. TBD.