Update starcgen for new types

[lostluck]

Updates the starcgen code generator to better handle Pointer, Map, and Array types.

• Slice suffix for function names is now a prefix to avoid collisions in ordering with Maps of Slice of Arrays or similar
• Filter out "universal" named types such as error.
• Filter out Beam internal types (beam.X/typex.X and similar)
• Improve test coverage for both the templates and the analyzer.
• Regenerate the beam shims with go generate ./...

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Post-Commit Tests Status (on master branch)

Lang	SDK	Apex	Dataflow	Flink	Gearpump	Samza	Spark
Go		---	---	---	---	---	---
Java
Python		---			---	---	---

[lostluck]

R: @aaltay Please review.
The material changes are in the files under sdks/go/pkg/beam/util/. The rest are just the consequent generated code changes.

[lostluck]

Run Go PreCommit

[aaltay]

MapOfTypeName -> MapOfKeyTypeName_ValueTypeName ?

[lostluck]

Done. Nice catch!

[lostluck]

The Jenkin's environment appears to be interestingly configured due to GoGradle, so the tests for the shim-generator are unable to handle imports reliably there. They work fine locally.

I've opted to add special casing to check if that code can succeed first, and skip the test if not. It's sufficient that they run every time I do go test ./... locally.