Update test infra, get rid of gulp

[eugef]

No description provided.

[github-actions]

Coverage after merging test_infra_update into master will be

76.83%

Coverage Report

File	Stmts	Branches	Funcs	Lines	Uncovered Lines
lib
http-mock.js	100%	100%	100%	100%
mockEventEmitter.js	100%	100%	100%	100%
mockRequest.js	97.35%	95.41%	96.97%	98.48%	55–56, 579–580, 586–587, 80, 91
mockResponse.js	89.18%	81.43%	95.92%	91.61%	156–159, 162–163, 172, 172, 172, 174–175, 182, 182, 182–185, 185, 185–188, 190–191, 193, 196–200, 203, 230, 254, 287, 321, 387, 387, 46–47, 49–50, 505, 534, 570, 660, 667, 674, 723, 742–743, 759, 763
mockWritableStream.js	81.82%	100%	80%	83.33%	11
utils.js	88.89%	50%	100%	100%	4
lib/express
mock-application.js	30.59%	0%	5%	42.37%	10–11, 15–17, 17, 17–22, 27–30, 32, 32, 32–33, 36, 38, 52, 56, 60, 64, 64, 64–65, 68–69, 73, 77, 8, 81, 85, 89, 9, 94, 99
mock-express.js	52.63%	100%	0%	58.82%	14, 16–17, 19, 23, 27–28
mock-request.js	19.88%	0%	0%	34.74%	101, 101, 101, 105, 109, 111, 111, 111–112, 115–116, 116, 116, 118, 122, 126, 128, 128, 128–129, 132, 132, 132–133, 136, 136, 136–137, 139, 139, 139, 143, 147–148, 150, 150, 150, 150, 150–151, 154, 154, 154, 154, 154, 154–155, 155, 155, 158, 16, 162, 166, 166, 166–167, 17, 17, 17, 17, 20, 20, 20, 22, 29–30, 34–35, 41–42, 48–49, 55–56, 56, 56–57, 59, 63, 63, 63–64, 64, 64–65, 65, 65, 67, 67, 67, 67, 67–68, 70, 70, 70–71, 73, 73, 73–74, 77, 81, 83, 83, 83–84, 87, 91–92, 92, 92–93, 97
lib/express/utils
define-getter.js	100%	100%	100%	100%
lib/node
_http_incoming.js	13%	0%	0%	21.67%	100, 100, 100, 102, 104, 107, 107, 107, 109, 11, 112, 118, 118, 118–119, 13–20, 22, 24–26, 28–29, 31–32, 34, 36, 47, 47, 47–48, 53, 53, 53, 53, 53, 56, 56, 56–58, 60–61, 64–69, 75–76, 76, 76, 76, 76, 76, 76, 76, 76, 76, 76, 76, 76, 76, 76, 79, 79, 79, 81, 84, 86
_http_server.js	100%	100%	100%	100%
http.js	100%	100%	100%	100%