add query cmds and aspects

inspections.rst

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+Experiments with Bazel queries and aspects to inspect targets
+============================================================= 
+
+- Exploring targets
+
+  .. code-block:: bash
+
+    bazel query //tools/sphinx/codelinks/...
+
+- Find all ``codelinks_analyse`` rule type
+
+  .. code-block:: bash
+
+    bazel query 'kind(codelinks_analyse, //...)'
+
+- Print out the source files of ``codelinks_analyse`` target in ``//projects/acdc/ac``
+
+  .. code-block:: bash
+
+    bazel build //projects/acdc/ac:codelinks_analyse --aspects print.bzl%print_aspect
+
+- print out the source files of all ``codelinks_analyse`` targets used in the repo
+
+  .. code-block:: bash
+
+    bazel build $(bazel query "kind(codelinks_analyse, //...)") --aspects //:print.bzl%print_aspect
+
+- Find all targets that depends on file ``projects/acdc/ac:src/ac.c``
+
+  .. code-block:: bash
+
+    bazel query "rdeps(//..., //projects/acdc/ac:src/ac.c)"
+
+- Find which targets of a specific kind depend on a certain file
+
+  .. code-block:: bash
+
+    bazel query "kind(codelinks_analyse, rdeps(//..., //projects/acdc/ac:codelinks.toml))"

print.bzl

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+# Reference: https://bazel.build/extending/aspects
+
+def _print_aspect_impl(target, ctx):
+
+    print("+ print_aspect_impl")
+    print("Target: " + str(target.label))
+    print(ctx.rule.kind)
+    target_kind = getattr(ctx.attr, "target_kind", "")
+    print("Target kind from attr: " + target_kind)
+    # Make sure the rule has a srcs attribute.
+    if target_kind != ctx.rule.kind:
+       return []
+
+    if hasattr(ctx.rule.attr, 'srcs'):
+        # Iterate through the files that make up the sources and
+        # print their paths.
+        for src in ctx.rule.attr.srcs:
+            for f in src.files.to_list():
+                print(f.path)
+    print("- print_aspect_impl")
+    return []
+
+print_aspect = aspect(
+    implementation = _print_aspect_impl,
+    attr_aspects = ['srcs'],    # the edge to track
+    attrs = {
+        'target_kind': attr.string(
+            default = 'codelinks_analyse',),
+    }
+    # required_providers = [CcInfo],
+)