Enqueue calls with the OkHttp client's ExecutorService

[zack13532]

In case a user wants to process many simultaneous requests for a GetFeaturesBatch call, provide an option to use the client's ExecutorService (obtained from the OkHttp client's dispatcher) to do the pre-processing work of constructing and enqueueing the requests.

Considerations:

• This work is fairly lightweight, so this new option should really only be used if there is a huge number of requests in the batch, and we're using an ExecutorService that can efficiently parallelize the work.
  • Note that the dispatcher already uses an ExecutorService to (potentially) take advantage of multi-threading for the actual work of making HTTP calls; this PR allows you to also use the same ExecutorService for the pre-processing steps as well.
• It is unlikely that one would want to have multiple ExecutorServices in operation at once, hence the decision to reuse the one in use by the OkHttp client which will already be handling concurrency.

Example:

ThreadPoolExecutor executor = new ThreadPoolExecutor(...);
Dispatcher dispatcher = new Dispatcher(executor);
OkHttpClient okHttpClient = OkHttpClient.Builder()
    .dispatcher(dispatcher)
    .build();

TectonClient client = new TectonClient(TECTON_URL, TECTON_API_KEY, okHttpClient);

fixes gh-50

[zack13532]

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• Enqueue calls with the OkHttp client's ExecutorService #93 : 2 dependent PRs (#94 , #97 ) 👈 (View in Graphite)
• Pass index into callback #96
• Set request index as a header #95
• Use tags to assign responses to result list #92
• Remove usage of parallelStream in favor of stream #91
• Update changelog for 0.9.2 #90
• Update readme with usage examples and bump version #89
• main

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