Add Kotlin web examples (500USD Bounty)

[lihaoyi]

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From the maintainer Li Haoyi: I'm putting a 500USD bounty on this issue, payable by bank transfer on a merged PR implementing this.

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The goal of this ticket is to add example/kotlinlib/web example tests for using Kotlin for web development, mirroring the example/javalib/web and example/scalalib/web folders. Each language has different things worth documenting for web development, so it's not a direct 1:1 comparison, but example/kotlinlib/web should have the following:

1. 1-hello-ktor, a hello-world example using Kotlin and KTor to set up a web server serving a single "<h1>Hello, World!</h1>" web page, in the spirit of example/javalib/web/2-hello-spring-boot
2. 2-todo-ktor, an implementation of the common TodoMVC demo application, in the spirit of example/javalib/web/3-todo-spring-boot

Like the existing tests in example/javalib/web and example/scalalib/web, the ktor examples should be exercised via the example test commands going through unit tests, integration tests, and "manual" tests using runBackground and curl

[lihaoyi]

Closing in favor of #3611