Command added to modifiy the web server rewrites configurtion

[ajithkumar-maragathavel]

Description

Affected Pages
https://devdocs.magento.com/mftf/docs/getting-started.html#nginx-settings

Added a CLI command to modify the web server rewrites configuration and also added cache clean command after changing the values.

Note:
I have also verified the CLI command to modify the web server rewrites works as expected in my local development evironment.

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/verification tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)
• Changes to Framework doesn't have backward incompatible changes for tests or have related Pull Request with fixes to tests

[coveralls]

Coverage remained the same at 56.074% when pulling ee2b7ac on ajithkumar-maragathavel:web-server-rewrites into d890e05 on magento:develop.

[lbajsarowicz]

✔️ Interesting change. It's assumed that rewrites are turned on, but it's worth to add this explicitly.

[tomreece]

Approved by @dobooth also.