Bugfix for fork-ts-checker-webpack-plugin and TypeScript 3.8 Type-Only Imports/Exports

[nelsonni]

Description:

The addition of "importsNotUsedAsValues": "preserve" in tsconfig.json (following the example ESLint configuration for the fork-ts-checker-webpack-plugin module), introduced type errors for import/exports of TypeScript type definitions. Further details of the error is documented in issue #308.

Fixing this issue also revealed additional errors, including ESLint linting being applied to non-code files (.svg, .png, .json) with repeated errors for each such file within the Synectic codebase indicating:

src/assets/alt_folder.svg
[unknown]: Parsing error: "parserOptions.project" has been set for @typescript-eslint/parser.
The file does not match your project config: src/assets/alt_folder.svg.
The extension for the file (.svg) is non-standard. It should be added to your existing "parserOptions.extraFileExtensions".

This error is documented in TypeStrong/fork-ts-checker-webpack-plugin#453, and requires fine-grain configuration of ESLint options used by the fork-ts-checker-webpack-plugin so that it does not aggressively lint all files.

This PR resolves #308, and signifies the following version changes:

• MAJOR version increase
• MINOR version increase
• PATCH version increase

Changes:

This PR makes the following changes:

• Converts all import statements for TypeScript type definition files (e.g. src/types.d.ts) to use TypeScript 3.8 import type statements.
• Narrow ESLint file glob in fork-ts-checker-webpack-plugin configs to only .ts, .tsx, and .js files.
• Remove ESLint import/named rule override for react-dnd/XYCoord, which was fixed in Defines the XYCoord interface in React-Dnd package react-dnd/react-dnd#1454.
• Remove ESLint @typescript-eslint/no-var-requires rule override for webpack.renderer.config.js file, since updates to @typescript-eslint have now restricted the no-var-requires rule to only apply to TS files.
• Increase TSConfig target to ES2018 (ECMAScript 2018 also known as ES9) for additional features such as asynchronous iterators, Promise.prototype.finally library, Unicode property escapes in regular expressions, RegExp lookbehind assertions, Object Rest/spread properties, RegExp named capture groups, and s 'dotAll' flag for regular expressions.

Checklist:

Before submitting this PR, I have verified that my code:

• Resides on a fix/ or feature/ branch that was initially branched off from development.
• Passes code linting (yarn lint) and unit testing (yarn test).
• Successfully builds a distribution package (yarn package).

Additionally, I have verified that:

• My name is listed in the Contributors section, or this PR includes a request to add my name.
• I have read and am aware of the CONTRIBUTING guide for this project.