-cdn -json should return true or false

[brenocss]

httpx version:

v1.1.5

Current Behavior:

echo 'google.com' | httpx -cdn -json | jq .cdn

null

Expected Behavior:

echo 'google.com' | httpx -cdn -json | jq .cdn

false

Use case

echo 'google.com
hackerone.com' | httpx -json >> log.json

echo 'google.com
hackerone.com' | httpx -cdn -json >> log.json

# Get all hosts's that is from any cdn
cat log.json | jq 'select(.cdn==true).url'

# Get all hosts's that isn't from any cdn
cat log.json | jq 'select(.cdn==false).url'
# cat log.json | jq 'select(.cdn!=true).url' doesn't work because it returns null with or without the -cdn flag, getting invalid results 

[ehsandeep]

@brenocss this feature will be updated with #492, so instead of returning true/false, it will return the name of the cdn.