Simplify the dev environment setup instructions by reusing Compose files (#7254)

The advantages of this are as follows:

* It's much easier for a developer to use one `docker compose up`
command to bring everything up than to run a custom command for each
service.

* We eliminate possible divergence of configuration (e.g. versions,
command-line parameters) between what we actually use and what's listed
in the documentation.

* It makes it easier to update the developer guide if new dependencies
are introduced.

* And speaking of new dependencies, we have KeyDB now, which hasn't been
added to the dev guide.

The disadvantage is that we have to run an extra copy of the CVAT
server, because otherwise OPA can't fetch its rules. I don't think it's
a significant issue, since it doesn't prevent you from debugging
anything.

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### Motivation and context
<!-- Why is this change required? What problem does it solve? If it
fixes an open
issue, please link to the issue here. Describe your changes in detail,
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Working on #7245, I realized that I don't want to add another custom
command for running Redis in the development environment to the dev
guide. So I wanted to remove the custom commands entirely.

### How has this been tested?
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Include details of your testing environment, and the tests you ran to
see how your change affects other areas of the code, etc. -->
By manually following the updated instructions.

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- [x] I submit my changes into the `develop` branch
- ~~[ ] I have created a changelog fragment~~ <!-- see top comment in
CHANGELOG.md -->
- [x] I have updated the documentation accordingly
- ~~[ ] I have added tests to cover my changes~~
- [x] I have linked related issues (see [GitHub docs](

https://help.github.com/en/github/managing-your-work-on-github/linking-a-pull-request-to-an-issue#linking-a-pull-request-to-an-issue-using-a-keyword))
- ~~[ ] I have increased versions of npm packages if it is necessary

([cvat-canvas](https://github.com/opencv/cvat/tree/develop/cvat-canvas#versioning),

[cvat-core](https://github.com/opencv/cvat/tree/develop/cvat-core#versioning),

[cvat-data](https://github.com/opencv/cvat/tree/develop/cvat-data#versioning)
and

[cvat-ui](https://github.com/opencv/cvat/tree/develop/cvat-ui#versioning))~~

### License

- [x] I submit _my code changes_ under the same [MIT License](
https://github.com/opencv/cvat/blob/develop/LICENSE) that covers the
project.
  Feel free to contact the maintainers if that's a concern.

Author: SpecLad

docker-compose.ci.yml

@@ -23,8 +23,3 @@ services:
       GITHUB_RUN_ID:
     volumes:
       - ${HOST_COVERAGE_DATA_DIR}:${CONTAINER_COVERAGE_DATA_DIR}
-
-  cvat_redis:
-    ports:
-      - 6379:6379
-

docker-compose.dev.yml

@@ -104,3 +104,7 @@ services:
   cvat_opa:
     ports:
       - '8181:8181'
+
+  cvat_redis:
+    ports:
+      - '6379:6379'

site/content/en/docs/contributing/development-environment.md

@@ -152,25 +152,21 @@ description: 'Installing a development environment for different operating syste
   >
   > Perform this action before installing cvat requirements from the list mentioned above.
 
-- Install [Docker Engine](https://docs.docker.com/engine/install/ubuntu/) and [Docker-Compose](https://docs.docker.com/compose/install/)
+- Install [Docker Engine](https://docs.docker.com/engine/install/ubuntu/) and [Docker Compose](https://docs.docker.com/compose/install/)
 
-- Pull and run Open Policy Agent docker image:
+- Start service dependencies:
 
   ```bash
-   docker run -d --rm --name cvat_opa_debug -p 8181:8181 --network=host openpolicyagent/opa:0.45.0-rootless \
-   run --server --set=decision_logs.console=true --set=services.cvat.url=http://localhost:7000 \
-   --set=bundles.cvat.service=cvat --set=bundles.cvat.resource=/api/auth/rules
+  docker compose -f docker-compose.yml -f docker-compose.dev.yml up -d --build \
+    cvat_opa cvat_db cvat_redis cvat_server
   ```
 
-- Pull and run PostgreSQL docker image:
+  Note: this runs an extra copy of the CVAT server in order to supply rules to OPA.
+  If you update the OPA rules, rerun this command to recreate the server image and container.
 
-  ```bash
-  docker run --name cvat_db_debug -e POSTGRES_HOST_AUTH_METHOD=trust -e POSTGRES_USER=root \
-  -e POSTGRES_DB=cvat -p 5432:5432 -d postgres
-  ```
-
-  Note: use `docker start/stop cvat_db_debug` commands to start and stop the container.
-  If it is removed, data will be removed together with the container.
+  Note: to stop these services, use
+  `docker compose -f docker-compose.yml -f docker-compose.dev.yml down`.
+  You can add `-v` to remove the data, as well.
 
 - Apply migrations and create a super user for CVAT: