Support for `bootTestRun` task

[desiderantes]

Spring Boot 3.1.x added support for configuring Testcontainers for local development via a separate Main class in the test source set, and a separate task called bootTestRun that executes with that main class. Seems like an ideal config for generating openapi definitions.

[jgooley-sh]

As a workaround until it is supported more explicitly I was able to get it working for me by doing this:

openApi {
    customBootRun {
        mainClass = 'com.sidecarhealth.expservice.TestApplication'
        classpath = sourceSets.main.runtimeClasspath + sourceSets.test.runtimeClasspath
    }
}