[WIP] Improves e2e test, adds mod files for standalone run

[M4tteoP]

Work in progress:
The following command is now running:

go run github.com/corazawaf/coraza/v3/http/e2e --proxy-hostport localhost:8080 --httpbin-hostport localhost:8081

But go mod tidy run under testing/e2e/ submodule is failing, even if the test itself is working:

▶ go mod tidy
go: finding module for package github.com/corazawaf/coraza/v3/http/e2e/runner
github.com/corazawaf/coraza/v3/testing/e2e tested by
	github.com/corazawaf/coraza/v3/testing/e2e.test imports
	github.com/corazawaf/coraza/v3/http/e2e/runner: module github.com/corazawaf/coraza/v3@latest found (v3.0.0), but does not contain package github.com/corazawaf/coraza/v3/http/e2e/runner

▶ go test -run ^TestE2e$ github.com/corazawaf/coraza/v3/testing/e2e
ok  	github.com/corazawaf/coraza/v3/testing/e2e	3.933s

[jcchavezs]

Do you mind rebasing this PR @M4tteoP ?

[codecov]

Codecov Report

Patch coverage has no change and project coverage change: +0.41 🎉

Comparison is base (cc4ec80) 81.57% compared to head (0c769c3) 81.98%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #822      +/-   ##
==========================================
+ Coverage   81.57%   81.98%   +0.41%     
==========================================
  Files         158      156       -2     
  Lines        8959     8711     -248     
==========================================
- Hits         7308     7142     -166     
+ Misses       1406     1339      -67     
+ Partials      245      230      -15     

Flag	Coverage Δ
default	76.67% <ø> (+0.10%)	⬆️
examples	25.66% <ø> (ø)
ftw	47.11% <ø> (ø)
ftw-multiphase	49.25% <ø> (ø)
tinygo	74.85% <ø> (+2.20%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

see 2 files with indirect coverage changes

☔ View full report in Codecov by Sentry.
📢 Do you have feedback about the report comment? Let us know in this issue.

[M4tteoP]

I had to add it because actually the /coraza/v3/http/e2e/runner package is not just inside the remote coraza/v3.
What is strange is that, removing the replace and updating coraza to v3.0.2 inside this submodule it ends up with ambiguous import: found package github.com/corazawaf/coraza/v3/testing/e2e in multiple modules

[M4tteoP]

Superseded by #841, thanks @jcchavezs 🙇‍♂️