Src path in v0

[TwitchBronBron]

• Renames pathAbsolute to srcPath to align with the naming change in v1.
• changes all internal calls to getFileByPathAbsolute to getFile
• adds pathAbsolute getter and setter to provide backwards compatibility support.

There's a small chance that this is a breaking change to plugins, but since we have the ability to lock bsc versions in vscode, I consider these acceptable risks.

• if a plugin locks to an exact version of bsc, and vscode updates to a new version of bsc, the diagnostics produced by the latest bsc might cause the plugin to crash when looking for pathAbsolute.

NOTE: I tested this change while using bslint against the fubo codebase, and it still works, so I'm pretty comfortable with this change not breaking back-compat for most projects.