_content/solutions: add Temporal to companies using Go

[yuandrew]

This change adds Temporal to the "Companies using Go" section on the
go.dev home page and case studies page.

Temporal's open source server is written primarily in Go:
https://github.com/temporalio/temporal

And one of its most popular SDKs is the Go SDK:
https://github.com/temporalio/sdk-go

The change also adds Temporal logo assets for light and dark themes.

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Patch Set 1:

(1 comment)

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