feat(gax): add ResumableUploadCallable and ResumableUploadCallSettings - #14052

It is highly recommended to validate that chunkSize is positive when it is configured. This prevents invalid configurations (such as negative or zero chunk sizes) from being set and causing runtime failures during uploads.

    public Builder<RequestT, ResponseT> setChunkSize(Integer chunkSize) {
      if (chunkSize != null) {
        com.google.common.base.Preconditions.checkArgument(
            chunkSize > 0, "chunkSize must be positive: %s", chunkSize);
      }
      this.chunkSize = chunkSize;
      return this;
    }

It is highly recommended to validate that totalBytes is non-negative when configured. This prevents invalid negative values from being set.

    public Builder<RequestT, ResponseT> setTotalBytes(Long totalBytes) {
      if (totalBytes != null) {
        com.google.common.base.Preconditions.checkArgument(
            totalBytes >= 0, "totalBytes must be non-negative: %s", totalBytes);
      }
      this.totalBytes = totalBytes;
      return this;
    }

The cast (ApiCallContext) null is redundant because there is only one 4-argument overload of futureCall, so the compiler can resolve the method call unambiguously. Removing the redundant cast improves code readability.

The casts (ResumableUploadCallSettings<RequestT, ResponseT>) null and (ApiCallContext) null are redundant because there is only one 4-argument overload of futureCall. Removing them simplifies the code and improves readability.

  public ApiFuture<ResponseT> futureCall(RequestT request, InputStream payload) {
    return futureCall(request, payload, null, null);
  }

The cast (ApiCallContext) null is redundant because there is only one 4-argument overload of call. Removing it improves readability.

The casts (ResumableUploadCallSettings<RequestT, ResponseT>) null and (ApiCallContext) null are redundant because there is only one 4-argument overload of call. Removing them simplifies the code.

  public ResponseT call(RequestT request, InputStream payload) {
    return call(request, payload, null, null);
  }