Support require instruction as module import

[gurobokum]

Pull Request Description

Support require expression for being able to use dependant basegl-loader with source code which contains importing with require() syntax
For example in webpack loader chaining where previous one produces ES5 and bellow source code (by default TypeScript produces ES3)

Important Notes

• Return signature of getAndRemoveLibImports has been changed: additional VariableDeclaration node can appear in the list
• gulp dependency tag has been changed from next to latest cause next is missed in https://registry.npmjs.org

Checklist

Please include the following checklist in your PR:

• The documentation has been updated if necessary.
• The code conforms to the Luna TypeScript Style Guide.
• The code has been tested where possible.

[gurobokum]

Let me clarify the main reason of the PR
Here if libRefs doesn't contain variable namespace name the callback isn't called
So basegl->expr is not parsed if basegl was declared as let basegl = require('basegl') what happens on ES3 webpack ts-loader processing

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