* Support none keyword in log-format escape
## What this PR does / why we need it:
ingress-nginx does not support disabling escaping of special characters in the nginx log. This PR exposes the setting to support that functionality.
## Types of changes
- [ ] Bug fix (non-breaking change which fixes an issue)
- [x] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing functionality to change)
- [ ] Documentation only
## Which issue/s this PR fixes
<!--
(optional, in `fixes #<issue number>` format, will close that issue when PR gets merged):
fixes #
-->
## How Has This Been Tested?
Followed the [getting-started](96b6228a6b/docs/developer-guide/getting-started.md) guide. Used ppa:longsleep/golang-backports on WSL Ubuntu to establish a golang-1.18 environment with latest docker and recommended kind. Built the dev-env successfully; had issues with make test, but they are entirely unrelated to anything I touched. Ultimate test was
```
FOCUS=log-format make kind-e2e-test
...
Ginkgo ran 1 suite in 6m29.7437865s
Test Suite Passed
```
## Checklist:
<!--- Go over all the following points, and put an `x` in all the boxes that apply. -->
<!--- If you're unsure about any of these, don't hesitate to ask. We're here to help! -->
- [x] My change requires a change to the documentation.
- [x] I have updated the documentation accordingly.
- [x] I've read the [CONTRIBUTION](https://github.com/kubernetes/ingress-nginx/blob/main/CONTRIBUTING.md) guide
- [x] I have added tests to cover my changes.
- [x] All new and existing tests passed.
I did not update docs/e2e-tests.md.
* gofmt -s ./internal/ingress/controller/config/config.go
