Better micro-infrastructure with Gradle composite builds

[gchristov]

What does this pull request change?

This PR migrates the project to composite builds, allowing independent build and deployment of each microservice. Full local deployment of everything is still supported.

How is this change tested?

Manually and with existing checks.

---

Writing Kotlin Multiplatform tests

[pulumi]

🍹 The Update for gchristov/proxy-web-service/prod was successful.

Resource Changes

    Name                      Type                            Operation
~   proxy-web-service-binary  docker:index/image:Image        update
~   proxy-web-service         gcp:cloudrunv2/service:Service  update

[pulumi]

🍹 The Update for gchristov/landing-page-web-service/prod was successful.

Resource Changes

    Name                             Type                            Operation
~   landing-page-web-service-binary  docker:index/image:Image        update
~   landing-page-web-service         gcp:cloudrunv2/service:Service  update

[pulumi]

🍹 The Update for gchristov/slack-service/prod was successful.

Resource Changes

    Name                  Type                            Operation
~   slack-service-binary  docker:index/image:Image        update
~   slack-service         gcp:cloudrunv2/service:Service  update

[pulumi]

🍹 The Update for gchristov/statistics-service/prod was successful.

Resource Changes

    Name                       Type                            Operation
~   statistics-service-binary  docker:index/image:Image        update
~   statistics-service         gcp:cloudrunv2/service:Service  update

[pulumi]

🍹 The Update for gchristov/self-destruct-service/prod was successful.

Resource Changes

    Name                          Type                            Operation
~   self-destruct-service-binary  docker:index/image:Image        update
~   self-destruct-service         gcp:cloudrunv2/service:Service  update

[pulumi]

🍹 The Update for gchristov/search-service/prod was successful.

Resource Changes

    Name                   Type                            Operation
~   search-service-binary  docker:index/image:Image        update
~   search-service         gcp:cloudrunv2/service:Service  update

[pulumi]

🍹 The Update (preview) for gchristov/slack-service/prod was successful.

Resource Changes

    Name                  Type                            Operation
~   slack-service-binary  docker:index/image:Image        update
~   slack-service         gcp:cloudrunv2/service:Service  update

[pulumi]

🍹 The Update (preview) for gchristov/search-service/prod was successful.

Resource Changes

    Name                   Type                            Operation
~   search-service-binary  docker:index/image:Image        update
~   search-service         gcp:cloudrunv2/service:Service  update

[pulumi]

🍹 The Update (preview) for gchristov/self-destruct-service/prod was successful.

Resource Changes

    Name                          Type                            Operation
~   self-destruct-service-binary  docker:index/image:Image        update
~   self-destruct-service         gcp:cloudrunv2/service:Service  update

[pulumi]

🍹 The Update (preview) for gchristov/statistics-service/prod was successful.

Resource Changes

    Name                       Type                            Operation
~   statistics-service-binary  docker:index/image:Image        update
~   statistics-service         gcp:cloudrunv2/service:Service  update