Fix assimp build with --dynamic_mode off (#4724)

Fixes linker issues when building with `--dynamic_mode off` that come
from missing symbols in the IO plugin libraries. The fix is to merge all
IO plugin sources directly into the `@assimp` target instead of building
them as separate cc libraries. This change is backward compatible since
the plugin libraries were not publicly visible. For the sake of logical
organization, I have kept the sources for each IO plugin as separate
`filegroup` targets that are merged into `srcs` for the `@assimp`
library target.

Signed-off-by: Shameek Ganguly <shameek@intrinsic.ai>

Author: shameekganguly

modules/assimp/5.4.3.bcr.3/MODULE.bazel

@@ -0,0 +1,12 @@
+module(
+    name = "assimp",
+    version = "5.4.3.bcr.3",
+    compatibility_level = 0,
+    bazel_compatibility = [">=7.2.1"],
+)
+
+bazel_dep(name = "bazel_skylib", version = "1.7.1")
+bazel_dep(name = "pugixml", version = "1.15")
+bazel_dep(name = "rapidjson", version = "1.1.0.bcr.20241007")
+bazel_dep(name = "rules_cc", version = "0.1.1")
+bazel_dep(name = "zlib", version = "1.3.1.bcr.6")