Refactor Building CI to track ldmx-sw

[tomeichlersmith]

This resolves #104

• add a new custom "dependabot" that checks for a new ldmx-sw release weekly and update the testing versions accordingly (replace the latest testing version if it is a patch release, append a new latest testing version otherwise)
• change backwards compatibility patches to be patch files from git diff rather than scripts
• have the AMD build happen on GitHub runners? <- not sure if I want to make this work but it is technically feasible won't do
• use denv for test building ldmx-sw
• use just as well so we respect the recipes in the justfile and don't have to update stuff here when testing

I did test runs of ./ci/test-ldmx-sw locally and it works. With the other builds happening right now (and the layer caching being broken I think?), the CI tests on GitHub were cancelled after waiting too long to be run.

[tomeichlersmith]

Alright, the test infrastructure is working as intended, but I have only been testing with ldmx/dev:latest (i.e. 4.2.2). After the latest build (https://github.com/LDMX-Software/dev-build-context/actions/runs/13638466534) finishes, I'll update to test run with ldmx/dev:edge to be able to develop the patches without having to wait for the builds.

[tomeichlersmith]

The minimum supported ldmx-sw version (MSLV) for this image is now v3.3.0. Technically, we could go lower if we don't build acts. The version of acts included between v3.2.1 and v3.2.12 is old enough that it does not compile with the newer compiler in this image.

The ldmx-sw versions <= v3.2.12 are old enough that I think we don't need to support development off of them anymore. We already have instructions for pushing developers to develop off of v4 anyways so I'm okay with bumping the MSLV from v3.0.0 to v3.3.0.