feat(create): support relative path from root as lerna create location

[fahslaj]

Description

Provides a few quality of life updates for the positional argument for lerna create:

• Allows use of a path relative to the root of the project (./packages/apps)
• Fixes issue matching with multi-segment paths (lerna create <loc> misrecords subpackage location #2520)
• No longer fails to match with configured workspace directories due to case sensitivity.
• Throws an explicit error when the location does not match a configured workspace directory. Previously, this would default to the first configured directory, which was misleading.
• Throws an explicit error when the "name" argument is not valid and it appears to look like a path (has a / in it). The error hints that the positional should be used instead and links to the create docs.

This does not add support for providing the path and name in one argument.

This is because the name argument must be valid according to npm-package-arg (https://www.npmjs.com/package/npm-package-arg) and can include a npm scope.

For example:
Incorrect:

lerna create packages/apps/my-package
lerna create ./packages/apps/my-package

Correct:

lerna create my-package packages/apps
lerna create my-package ./packages/apps
lerna create my-package /projects/my-repository-absolute-path/packages/apps

Motivation and Context

#2520
#3444

How Has This Been Tested?

This has been tested manually and covered with many e2e tests.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Chore (change that has absolutely no effect on users)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.