Update httpRequestManager method declaration

[Mael-RABOT]

Update httpRequestManager method declaration

• [x] Fix 1 : Remove the auto definition of argument, e.g.: requestType : HttpRequestType = "GET"

public async send(url : string, requestType : HttpRequestType = "GET", headers : Headers = new Headers(), body : string = "")

[Chi-Iroh]

This default parameter allowed caller not to explicitly write GET, which reduces readability and is more error-prone, thus I removed it.