Bring JaegerThrift exporter and factory into this repo

[breedx-splk]

For good reason, the upstream agent is looking to remove the JaegerThriftSpanExporter (and supporting factory/builders). Splunk should probably get ahead of this upstream issue:
open-telemetry/opentelemetry-java-instrumentation#1973
and copy the classes into this repo so that they can be removed there.

[breedx-splk]

We didn't get ahead of it. :). Anyway, here's the PR that removed it: open-telemetry/opentelemetry-java-instrumentation#2073

[mateuszrzeszutek]

Hmm, isn't it already here? https://github.com/signalfx/splunk-otel-java/blob/main/custom/src/main/java/com/splunk/opentelemetry/jaeger/JaegerThriftSpanExporterFactory.java

It was added to this repo before otel-java-instr had it

[breedx-splk]

Ok, the factory is here but the JaegerThriftSpanExporter is not (yet). The factory imports it from upstream (I think).

[jkwatson]

JaegerThriftSpanExporter is in the main java repo: https://github.com/open-telemetry/opentelemetry-java/tree/master/exporters/jaeger-thrift

[breedx-splk]

Aha! Then I think we are good. Thanks y'all.