[REQUEST] Web requests should set keepAlive to `true`

[kevinfoley]

Currently, in HttpSignaling, the keepAlive property for all web requests is set to false. When connecting from Render Streaming to a custom web server, if the server respects the keepAlive setting, this will prevent the TCP connection from remaining open and require establishing a new TCP connection for each request. This can cause significant extra networking strain and latency.

This can be solved by setting keepAlive to true, or by exposing a property in the inspector for the developer to choose whether to enable keepAlive.

[karasusan]

@kevinfoley Sure, I will fix them. Thanks.

[karasusan]

memo: URS-379