Fix c-blosc2 (bazelbuild#1773)

AcademySoftwareFoundation/openexr#1604 revealed
that the c-blosc2 module still has some linker issues. This PR fixes
those issues. This PR is an improvement of the c-blosc2 model at version
2.12.0.

In detail, missing c files were added to the c-blosc2 target. Also,
textual_hdrs were reworked. Besides this cc_tests targets were
introduced to make sure the whole thing works across different systems.

The defines `HAVE_PLUGINS` and `HAVE_ZSTD` were added. Without the
define `HAVE_PLUGINS` zfp plugin is not initialized (which is required
by OpenEXR).

@phaedon Maybe this fixes also some issues on your side ;). You can
create a PR and add yourself as a maintainer to this module if you like.
This way you will get notified if "improvements" are made or at least it
gives you a chance to veto changes ;). Furthermore, the PR policy was
changed in a way that a positive review of a maintainer can lead under
some circumstances to a successful merge without the need to get a
review of one of the "admins/repo owners"

modules/c-blosc2/2.12.0.bcr.2/MODULE.bazel

@@ -0,0 +1,10 @@
+module(
+    name = "c-blosc2",
+    version = "2.12.0.bcr.2",
+    compatibility_level = 1,
+)
+
+bazel_dep(name = "lz4", version = "1.9.4")
+bazel_dep(name = "platforms", version = "0.0.9")
+bazel_dep(name = "zlib-ng", version = "2.0.7")
+bazel_dep(name = "zstd", version = "1.5.6")