feat: Allow Disabling the default Exporter

[arriIsHere]

Which problem is this PR solving?

We have had a few requests come in asking for the ability to disable the default exporter. This makes it possible through a new property in the configuration.

Short description of the changes

This adds a new SDK configuration property disableDefaultTraceExporter that, when set to true will disable the default exporter.

How to verify that this has the expected result

Provide this boolean as true in an example and note no events are sent to honeycomb.

[MustafaHaddara]

I am also not married to the name but I think this is one of those things where there is no perfect name and we could spend weeks bikeshedding about it.

The current name is Fine™️

I vote we ship it!

[wolfgangcodes]

This works as advertised (esp in conjunction with traceExporters option). I'm curious if it's more inline with exceptions where folks can set the default exporter like this:

const sdk = new HoneycombWebSDK({
    apiKey: 'someKey // Replace with your Honeycomb Ingest API Key
    serviceName: 'coolApp', 
    defaultExporter: MyDefaultTraceExporter(),
    traceExporters: [ExporterMcExporteryFace(), TraceExporter2()]
    ...
    }

And disable it with:

const sdk = new HoneycombWebSDK({
    apiKey: 'someKey // Replace with your Honeycomb Ingest API Key
    serviceName: 'coolApp', 
    defaultExporter: null,
    traceExporters: [ExporterMcExporteryFace(), TraceExporter2()]
    ...
    }

I wonder if @pkanal or @martin308 have any instincts here. 🤔

[pkanal]

@wolfgangcodes I'm strongly in favour of the boolean option, a null option makes me nervous about null/undefined checks and this feels really lightweight and explicit to me!

[arriIsHere]

Only thing I am going to change is push to unshift so that it behaves the same way it does in the previous code.

[wolfgangcodes]

We may want a check/logger statement here so that if folks disable the default exporter AND the don't provide any other exporters, there's at least something that's like console.warn("You gots no exporters configured.")