Use `$is_args` variable for appending query parameters when configuring Rewrites.

[salonichf5]

Is your enhancement request related to a problem? Please describe.

We currently use ? to add query params for URLRewrite. Nginx provides a flag to verify if query params exist called $is_args. We should be making use of the $is_args instead of ? to make standardize.

What would you like to be added:
Use the $is_args variable for adding query params to a URL instead of ? when creating rewrites

Why this is needed:
To use standard variables for evaluating urls

[salonichf5]

Closing this story as won't do since after initial investigation, we cannot use $is_args for rewrite filters as it leads to encoding the special character. Mentioning ? explicitly works best in case of rewrites since args get pre-processed multiple times before return is done.

with the ? explicitly mentioned, it results in

curl --resolve cafe.example.com:$GW_PORT:$GW_IP http://cafe.example.com/:$GW_PORT/latte/prices\?test\=v1 --include
Handling connection for 8080
HTTP/1.1 200 OK
Server: nginx
Date: Tue, 07 Jan 2025 19:17:17 GMT
Content-Type: text/plain
Content-Length: 169
Connection: keep-alive
Expires: Tue, 07 Jan 2025 19:17:16 GMT
Cache-Control: no-cache

Server address: 10.244.0.80:8080
Server name: coffee-6db967495b-lrglc
Date: 07/Jan/2025:19:17:17 +0000
URI: /prices?test=v1
Request ID: 1db21172fa5e64770dfcaf3f0ad3f1c8

with $is_args it results in

curl --resolve cafe.example.com:$GW_PORT:$GW_IP http://cafe.example.com/:$GW_PORT/latte/prices\?test\=v1 --include
Handling connection for 8080
HTTP/1.1 200 OK
Server: nginx
Date: Tue, 07 Jan 2025 19:17:17 GMT
Content-Type: text/plain
Content-Length: 169
Connection: keep-alive
Expires: Tue, 07 Jan 2025 19:17:16 GMT
Cache-Control: no-cache

Server address: 10.244.0.80:8080
Server name: coffee-6db967495b-lrglc
Date: 07/Jan/2025:19:17:17 +0000
URI: /prices%3Ftest=v1
Request ID: 1db21172fa5e64770dfcaf3f0ad3f1c8