STITCH-1817 - Expose StitchServiceClient and add AwsServiceClient

[edaniels]

No description provided.

[coveralls]

Pull Request Test Coverage Report for Build 5b5b729f2a60ed55eefc7acc

• 59 of 99 (59.6%) changed or added relevant lines in 22 files are covered.
• 2 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.4%) to 67.396%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
core/admin-client/src/main/java/com/mongodb/stitch/core/admin/services/ServiceConfigs.kt	0	1	0.0%
core/admin-client/src/main/java/com/mongodb/stitch/core/admin/services/rules/RulesResources.kt	0	1	0.0%
core/sdk/src/main/java/com/mongodb/stitch/core/internal/CoreStitchAppClient.java	0	4	0.0%
core/sdk/src/main/java/com/mongodb/stitch/core/services/internal/CoreStitchServiceClientImpl.java	0	4	0.0%
server/services/aws/src/main/java/com/mongodb/stitch/server/services/aws/internal/AwsServiceClientImpl.java	4	15	26.67%
core/services/aws/src/main/java/com/mongodb/stitch/core/services/aws/internal/CoreAwsServiceClient.java	12	31	38.71%

Files with Coverage Reduction	New Missed Lines	%
core/services/aws-ses/src/main/java/com/mongodb/stitch/core/services/aws/ses/internal/ResultDecoders.java	1	28.57%
core/services/aws-s3/src/main/java/com/mongodb/stitch/core/services/aws/s3/internal/ResultDecoders.java	1	18.18%

Totals
Change from base Build baas_android_sdk_c50bf2630941a609359063b0b6058f41ac8d3579:	-0.4%
Covered Lines:	1879
Relevant Lines:	2788

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💛 - Coveralls

[adamchel]

two nits

[adamchel]

[nit] testCallFunction

[adamchel]

[nit] revert