Better compartmentalize code that assumes no trailing "/"

[peterflynn]

The "canonical" folder path format used in DirectoryEntry.fullPath includes a trailing "/". However, we have some Brackets code that requires or generates paths in the opposite format. This cleans up several of those cases:

• Rename FileUtils.canonicalizeFolderPath() to stripTrailingSlash() since it actually makes paths NOT canonical. Old API is deprecated but left in place for now (it's used by several extensions -- I'll file bugs once this lands).
• Add warning to docs for two other APIs that return non-canonical paths: FileUtils.getNativeBracketsDirectoryPath() & FileUtils.getNativeModuleDirectoryPath()
• Indicate explicitly that ProjectManager._loadProject() / openProject() support receiving non-canonical paths
• Fix several ProjectManager APIs that used to return and/or receive non-canonical paths -- getInitialProjectPath(), _getWelcomeProjectPath(), updateWelcomeProjectPath(). No extensions use these APIs.
• Centralize code that touches "welcomeProjects" pref storage, for clarity

This is an incremental improvement. Not everything has been cleaned up:

• Some code still calls openProject() with non-canonical paths
• RecentProjects still works with non-canonical paths internally (including its pref storage)
• The list of previous "welcomeProjects" is still stored non-canonicalized
• ScopeManager (in JS code hints) still requires non-canonical paths in some places (while requiring canonical paths in others! 😂)
• The two getNative*() APIs above still return non-canonical paths -- though I think we can fix these soon. It will be safer to change these once we have the new filesystem because it's more careful about handling duplicated slashes.

[peterflynn]

@njx You might want to look at this if you have time, since it largely concerns the "welcome project" detection and the RecentProjects extension -- both of which I think you've worked on.

[JeffryBooher]

Any reason not to check the length here? Seems that we should make sure it isn't an empty string and is truthy before invoking the index operator.

[peterflynn]

Arrays in JS aren't length checked -- you just get undefined for outside of range indices. So the equality check is guaranteed to correctly evaluate to false for an empty string.

[peterflynn]

I'll re-add it though just so it's more explicit

[JeffryBooher]

Done with initial review. just a few minor nits.

[peterflynn]

@JeffryBooher Changes pushed -- let me know if you need me to address anything else

[JeffryBooher]

any reason why this isn't a public function in FileUtils.js? Seems handy to have for other modules/extensions to be able to use

[peterflynn]

@JeffryBooher I'm hoping we won't need to get people in the habit of manually normalizing paths. Even in Brackets today, folder paths from almost every API are guaranteed to end in "/" -- these ones ProjectManager deals with are among the few exceptions. And the newer file API we're working on will make that guarantee even more explicit.

[JeffryBooher]

Looks good. Unit/Integration tests pass. Merging

[peterflynn]

Thanks @JeffryBooher!