[github-actions]

• Add consolidated Language SDK compatibility matrix

Users comparing Language SDKs had to read each SDK's README, and the
per-SDK manifests lagged behind what the SDKs actually ship. One generated
matrix, split by authoring mode, shows what each SDK supports for a Dag
definition and for a Python Dag with stub TaskHandler.

• Add callbacks, listeners and provider operators to the SDK matrix

Users comparing Language SDKs could not see where callbacks, Airflow's
listener API and Python provider operators stand, because the matrix had
no dimension for any of them. Callbacks ask different things of an SDK per
authoring mode, so they are declared per mode like the other shared
capabilities.

• Address review on the Language SDK matrix generator

The umbrella capability and the authoring mode both read dag-definition,
which gives one name two meanings in the same manifest. A row's kind also
belongs in its entry key: state and capability names happen not to collide
today, so the lookup worked by accident rather than by design.

• Rename the dynamic-task-mapping dimension to mapped-tasks

The dimension is about whether a task can be a mapped task, which the
shorter name says directly and keeps the matrix row readable next to the
other task-level dimensions.

• Split callbacks into Dag-level and task-level dimensions

The callbacks of a Python Dag run whichever SDK executes its stub tasks, so
dag-callbacks is a Dag-definition concern only, while task-callbacks
stays declared per authoring mode. Drop provider-operators until ADR-0009
is accepted, and reuse the shared capabilities_doc fixture in the per-SDK
README tests.

• Fix the hook attribution in the matrix generation diagram

index.rst is written by update-lang-sdk-central-matrix from every SDK
in LANG_SDKS, not by the per-SDK README hook.

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(cherry picked from commit 719a685)

Co-authored-by: Jason(Zhe-You) Liu 68415893+jason810496@users.noreply.github.com