Mitigate autocompletion library influence to page loading performance

[vbaranov]

A part of #2390

Motivation

awesomplete js/css assets load synchronously contributing to page loading time. In addition, they are loaded from a 3d-party Github Repo directly.

Changelog

Enhancements

• the latest 1.1.2 version of awesomplete utility installed as a regular npm dependency.

Update: awesomplete package downgraded to 1.1.2 1fb6fa5 because of this issue LeaVerou/awesomplete#17193

• awesomplete-util.js copied to ./js/lib and cleared out with ES linter
• awesomplete.css loading is changed to async loading since autocompletion is not a part of critical css.

Advantages

• decreasing of every page loading time (➖ 300ms)
• independency of 3d-party Github repo

Chore

• the last versions of css-loader and sass-loader deps are installed

Checklist for your PR

• I added an entry to CHANGELOG.md with this PR
• If I added new functionality, I added tests covering it.
• If I fixed a bug, I added a regression test to prevent the bug from silently reappearing again.
• I checked whether I should update the docs and did so if necessary
• If I added/changed/removed ENV var, I should update the list of env vars in https://github.com/poanetwork/blockscout/blob/master/docs/env-variables.md to reflect changes in the table here https://poanetwork.github.io/blockscout/#/env-variables?id=blockscout-env-variables

[coveralls]

Pull Request Test Coverage Report for Build 15116cbc-d74e-454b-a756-1caa93ad2d98

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 79.291%

---

Totals
Change from base Build 1806de47-e9a9-4846-8359-5e17fec6f30e:	0.0%
Covered Lines:	5165
Relevant Lines:	6514

---

💛 - Coveralls