- replaces content-type header by accept to match HTTP and avoid CORS preflight

[baywet]

Overview

The auto-complete feature is currently using the Content-Type request header.
Not only this is the wrong header to specify which format you want in return from the server, it also forces a CORS preflight which double the load per auto-complete "run" on the service, degrading the end user experience.
This pull request corrects the header usage.

Demo

Wrong:

Invoke-WebRequest -Uri "https://graphexplorerapi.azurewebsites.net/openapi?url=/&style=geautocomplete&graphVersion=v1.0" `
-Headers @{
"method"="GET"
  "authority"="graphexplorerapi.azurewebsites.net"
  "scheme"="https"
  "path"="/openapi?url=/&style=geautocomplete&graphVersion=v1.0"
  "user-agent"="Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.88 Safari/537.36"
  "accept"="*/*"
  "origin"="https://developer.microsoft.com"
  "sec-fetch-site"="cross-site"
  "sec-fetch-mode"="cors"
  "sec-fetch-dest"="empty"
  "referer"="https://developer.microsoft.com/"
  "accept-encoding"="gzip, deflate, br"
  "accept-language"="en-US,en;q=0.9,fr;q=0.8"
} `
-ContentType "application/json"

Right:

Invoke-WebRequest -Uri "https://graphexplorerapi.azurewebsites.net/openapi?url=/&style=geautocomplete&graphVersion=v1.0" `
-Headers @{
"method"="GET"
  "authority"="graphexplorerapi.azurewebsites.net"
  "scheme"="https"
  "path"="/openapi?url=/&style=geautocomplete&graphVersion=v1.0"
  "user-agent"="Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.88 Safari/537.36"
  "accept"="application/json"
  "origin"="https://developer.microsoft.com"
  "sec-fetch-site"="cross-site"
  "sec-fetch-mode"="cors"
  "sec-fetch-dest"="empty"
  "referer"="https://developer.microsoft.com/"
  "accept-encoding"="gzip, deflate, br"
  "accept-language"="en-US,en;q=0.9,fr;q=0.8"
} `

Notes

https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS#Simple_requests

Testing Instructions

Run GE, try the auto-complete feature.

[baywet]

CC @finsharp @bettirosengugi

[baywet]

CC @thewahome