Add Brotli compression support

[bloodf]

From vue-storefront created by Fifciu: vuestorefront/vue-storefront#4245

What is the motivation for adding / enhancing this feature?

Brotli compression is able to reduce file size even 29% more than GZIP. Currently, we use this package https://github.com/expressjs/compression with GZIP mode. This package has 2 PRs with Brotli support:

• feat: support brotli expressjs/compression#150
• feat: add brotli support expressjs/compression#156

I think it might be a good idea to append one of those PRs and make selecting between Brotli & GZIP configurable.

What are the acceptance criteria

• Append PR with Brotli to Compression package
• Make it configurable to select between GZIP & Brotli

Can you complete this feature request by yourself?

• YES
• NO

Which Release Cycle state this refers to? Info for developer.

Pick one option.

• This is a normal feature request. This should be available on https://test.storefrontcloud.io and then after tests this can be added to next Vue Storefront version. In this case Developer should create branch from develop branch and create Pull Request 2. Feature / Improvement back to develop.
• (Pick this option only if you're sure) This is an important improvement request for current Release Candidate version on https://next.storefrontcloud.io and should be placed in next RC version. In this case Developer should create branch from release branch and create Pull Request 3. Stabilisation fix back to release.
• (Pick this option only if you're sure) This is a critical improvement request for current Stable version on https://demo.storefrontcloud.io and should be placed in next stable version. In this case Developer should create branch from hotfix or master branch and create Pull Request 4. Hotfix back to hotfix.

Additional information