feat: allow non root docs()

[AlexanderLanin]

📌 Description

So far docs() was only callable from the root BUILD file. While that was intentional, this also prevents us from running docs() commands in order to test them properly.

Quite a lot of technical debt has accumulated due to this restriction we imposed. Notably:

• Finding needs_json from different places was not implemented
• Testlogs read everything from the module, but a non root docs() command will typically now know most of the linked requirements
• Generated documentation must not be placed into /_bazel but in <docs()-dir>/bazel

🚨 Impact Analysis

• This change does not violate any tool requirements
• ... is covered by existing tool requirements
• This change does not violate any design decisions
• Otherwise I have created a ticket for new tool qualification

✅ Checklist

• Added/updated documentation for new or changed features <-- intentionally skipped for now. Not sure we want that.
• Added/updated tests to cover the changes
• Followed project coding standards and guidelines

[github-actions]

License Check Results

🚀 The license check job ran with the Bazel command:

bazel run --lockfile_mode=error //src:license-check

Status: ⚠️ Needs Review

Click to expand output

[License Check Output]
Extracting Bazel installation...
Starting local Bazel server (8.6.0) and connecting to it...
INFO: Invocation ID: 871be269-da90-400d-8791-5a33e99f6edb
Computing main repo mapping: 
Computing main repo mapping: 
Loading: 
Loading: 0 packages loaded
Loading: 0 packages loaded
DEBUG: /home/runner/.bazel/external/rules_python+/python/private/repo_utils.bzl:101:16: 
rules_python:coverage_dep WARNING: rules_python's bundled coverage tool has no wheel for python_version=3.12.13, platform=ppc64le-unknown-linux-gnu. `bazel coverage` will produce empty lcov for py_test targets in this configuration. Either pin python_version to a version in the bundled set (see python/private/coverage_deps.bzl), or configure coverage manually via py_runtime.coverage_tool. See docs/coverage.md.
DEBUG: /home/runner/.bazel/external/rules_python+/python/private/repo_utils.bzl:101:16: 
rules_python:coverage_dep WARNING: rules_python's bundled coverage tool has no wheel for python_version=3.12.13, platform=riscv64-unknown-linux-gnu. `bazel coverage` will produce empty lcov for py_test targets in this configuration. Either pin python_version to a version in the bundled set (see python/private/coverage_deps.bzl), or configure coverage manually via py_runtime.coverage_tool. See docs/coverage.md.
DEBUG: /home/runner/.bazel/external/rules_python+/python/private/repo_utils.bzl:101:16: 
rules_python:coverage_dep WARNING: rules_python's bundled coverage tool has no wheel for python_version=3.12.13, platform=s390x-unknown-linux-gnu. `bazel coverage` will produce empty lcov for py_test targets in this configuration. Either pin python_version to a version in the bundled set (see python/private/coverage_deps.bzl), or configure coverage manually via py_runtime.coverage_tool. See docs/coverage.md.
DEBUG: /home/runner/.bazel/external/rules_python+/python/private/repo_utils.bzl:101:16: 
rules_python:coverage_dep WARNING: rules_python's bundled coverage tool has no wheel for python_version=3.12.13, platform=x86_64-unknown-linux-musl. `bazel coverage` will produce empty lcov for py_test targets in this configuration. Either pin python_version to a version in the bundled set (see python/private/coverage_deps.bzl), or configure coverage manually via py_runtime.coverage_tool. See docs/coverage.md.
Loading: 0 packages loaded
    currently loading: src
Loading: 0 packages loaded
    currently loading: src
WARNING: Target pattern parsing failed.
ERROR: Skipping '//src:license-check': no such target '//src:license-check': target 'license-check' not declared in package 'src' defined by /home/runner/work/docs-as-code/docs-as-code/src/BUILD
ERROR: no such target '//src:license-check': target 'license-check' not declared in package 'src' defined by /home/runner/work/docs-as-code/docs-as-code/src/BUILD
INFO: Elapsed time: 8.334s
INFO: 0 processes.
ERROR: Build did NOT complete successfully
ERROR: Build failed. Not running target

[github-actions]

The created documentation from the pull request is available at: docu-html