[5] Support Multiple Variant Globs

[TomStrepsil]

Issue

resolves #5

Details

• Move from variantGlob to variantGlobs in the configuration of the webpack plugin.
• The getVariantFiles module becomes getVariantPaths, returning a Set rather than array of objects. The separation of name and path (just to save unpicking this later) has been replaced for a simpler collection of paths, with the separation now happening at time of need in processVariantFiles using parse.
• Renamed some related variables for brevity/clarity e.g. filename, directory etc.
• Updated the express example to use posix character classes and braces for numeric matching in its variantGlobs, to cover support of such, and provide inspiration for those that may prefer this form.

Scout Rule:

• Avoid needlessly sending variantGlob to processVariantFiles in processPointCuts
• Fixed a typo in the webpack package README.md ("sinlge" -> "single")

Upgrade guide

This change will represent breaking changes in consumers of the webpack package.

The point cut configuration needs to be modified for the plugin thus:

• variantGlob option key is renamed to variantGlobs, and its value should be wrapped in []

CheckList

• PR starts with [ISSUE_ID].
• Has been tested (where required) before merge to main.