Allow option to send chunking specific params as custom header params

[thickl]

Type of issue

• Bug report
• Feature request
• Support request

Uploader type

• Traditional
• S3
• Azure

Feature Request

Feature request details

{why is this feature important, not just for you, but for many others?}
For request of traditional uploads, there is an option to set params to be sent within the body (see https://docs.fineuploader.com/branch/master/api/options.html#request.paramsInBody). For an internal project I need the possibility to include the params for chunking requests as custom headers instead, in order to avoid numerous pre-flight requests for cors.

For this purpose I require to configure the options for params in a different way, for example by replacing the option request.paramsInBody with request.paramsMode and a new option -> header | body | url. Of course this approach would cause a breaking change in the core options API, so I am open for another solution.
Optionally for request.header there should be an option to set a prefix for header params (i.e. 'x-upload-'). This could be also set as 'request.headerParamPrefix`.

[rnicholus]

Custome headers will not help you to avoid preflight requests. And with that I’m going to close this issue since that is the only obvious motivation for this proposal.

[rnicholus]

This should be covered by #1917.