Refactor recipe build flows

[dbast]

Refactoring the existing llvm build workflow into one:

• Merge llvmdev_win_builder.yml + llvmdev_win-64_conda_builder.yml into one to avoid code duplication
• Add input parameters to be able to select between recipes/platform to build
• Rename flow to llvmdev_build.yml as it contains nothing specific to windows and the code is just a generic conda package builder
• Add ${{ matrix.recipe }}-${{ matrix.platform }} to upload name to better differentiate artifacts
• Remove "x" from bash -elx {0} as that pollutes the Action log due to the implicit source "$CONDA/etc/profile.d/conda.sh calls in every step. Adding set -x explicitly into step code instead.
• Set run-post: false to avoid setup-miniconda cleaning up the Github Action VM as that is wiped after the run anyways
• Run the flow if it gets changed in PRs, to see a public verification that the changes are actually working
• Define concurrency so that repeated pushes to a PR will cancel all previous builds to save resources and have faster feedback.
• Add support for linux-64, linux-aarch64, osx-64, osx-arm64, win-64 builds via different native runner types
• With simple DAG: fast (5sec) check job produces a build matrix based on (event = {label, pr}, changed files, manual input). The check job logic is written in Python and can be further extended to influence the DAG.
• Flow can be triggered by
  • Changes to the workflow
  • Adding a label named "build" to random PRs (only maintainers can do that)
  • Manually via workflow dispatch and selecting the conda-platform + recipe via drop down menu (required merge of PR to be available)
• Aligned the up/download artifact steps

[dbast]

latest triggers in my fork of

• the llvmdev build https://github.com/dbast/llvmlite/actions/runs/13165284701
• the llvmlite build+test https://github.com/dbast/llvmlite/actions/runs/13173309450

the tests currently fail with libmambapy.bindings.specs.ParseError: Found invalid version predicate in "None".

[esc]

The latest test run for llvmlite on windows passed: https://github.com/dbast/llvmlite/actions/runs/13176019487 -- @dbast was missing tags from their fork.

[esc]

LGTM this has been tested across various runs. Any other issues to be addressed in subsequent PRs.