Remove variable syntax regex character ranges

[arbbakbenny]

What did you implement

Closes #6559 and #6997. Expand regex for variable syntax by removing fixed character ranges thus allowing non ascii characters as valid fallback values.

How can we verify it

Checkout to dea5ecc2a0406bc46eb38f6cb8dfc17363d90498 and run lib/classes/Variables.test.js::fallback and lib/plugins/print/print.test.js::should resolve fallback tests. Both should fail. Checkout to HEAD, tests should pass.

Given a serverless.yml

service: variables

provider:
  name: aws
  runtime: nodejs12.x
  profile: dev
  region: eu-central-1
  stage: dev
  environment:
    HELLO: world+
    DEFAULT: ${env:unused, '++++++'}
    JAPANESE: ${env:unused, 'システム管理者'}

functions:
  hello:
    handler: handler.hello

With hello content:

'use strict';

module.exports.hello = async event => {
  return {
    statusCode: 200,
    body: {
        message: 'Go Serverless v1.0! Your function executed successfully!',
        hello: process.env.HELLO,
        plus: process.env.DEFAULT,
        jap: process.env.JAPANESE
    },
  };
};

When invoking it should return resolved values.

Todos

• Write and run all tests
• Enable "Allow edits from maintainers" for this PR
• Update the messages below

Is this ready for review?: YES
Is it a breaking change?: It should be backward compatible so no.

[codecov-io]

Codecov Report

Merging #7431 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #7431   +/-   ##
=======================================
  Coverage   87.98%   87.98%           
=======================================
  Files         240      240           
  Lines        9064     9064           
=======================================
  Hits         7975     7975           
  Misses       1089     1089

Impacted Files	Coverage Δ
lib/plugins/print/print.js	98.5% <ø> (ø)	⬆️
lib/classes/Service.js	97.43% <ø> (ø)	⬆️

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[medikoo]

Thank you @arbbakbenny Looks great!