build(rust): link Rust CLI generators into program tests

Keep the original C translation units as declaration-only build shims while
the Rust CLI helper archive owns datagen and lorem. Track both Rust sources in
the program and test archive prerequisites, and link the helpers-only archive
into C test binaries that still provide their own file I/O and orchestration.
This preserves the existing C test harnesses while making the migrated helper
implementations the single definitions used by the binary and tests.

Test Plan:
- make -C programs zstd V=1
- make -C tests datagen V=1
- make -C tests test-rust-lib-smoke V=1
- git diff --check

Refs: programs/datagen.c, programs/lorem.c, tests/Makefile

tests/Makefile

@@ -110,7 +110,8 @@ RUST_CLI_DIR := $(RUST_DIR)/cli
 RUST_CLI_MANIFEST := $(RUST_CLI_DIR)/Cargo.toml
 RUST_CLI_HELPER_SOURCES := $(RUST_CLI_MANIFEST) $(RUST_CLI_DIR)/Cargo.lock \
                            $(RUST_CLI_DIR)/src/lib.rs \
-                           $(RUST_DIR)/src/timefn.rs $(RUST_DIR)/src/benchfn.rs
+                           $(RUST_DIR)/src/timefn.rs $(RUST_DIR)/src/benchfn.rs \
+                           $(RUST_DIR)/src/datagen.rs $(RUST_DIR)/src/lorem.rs
 RUST_CLI_HELPERS_TARGET_DIR := $(RUST_DIR)/target/cli-helpers
 RUST_CLI_HELPERS_STATICLIB := $(RUST_CLI_HELPERS_TARGET_DIR)/release/libzstd_cli_rs.a
 RUST_CLI_HELPERS_STATICLIB_32 := $(RUST_CLI_HELPERS_TARGET_DIR)/$(RUST_TARGET_32)/release/libzstd_cli_rs.a
@@ -380,7 +381,8 @@ $(RUST_LINK_TARGETS) $(RUST_LINK_TARGETS_32): $(RUST_HUF_C_MODE_STAMP)
 # prerequisite so `$^` places it after every C object referencing its symbols.
 RUST_CLI_LINK_TARGETS := fullbench fullbench-lib fullbench-dll fuzzer \
                          zstreamtest zstreamtest_asan zstreamtest_tsan \
-                         zstreamtest_ubsan paramgrill decodecorpus poolTests
+                         zstreamtest_ubsan paramgrill decodecorpus poolTests \
+                         datagen largeDictionary
 $(RUST_CLI_LINK_TARGETS): $(RUST_CLI_HELPERS_STATICLIB)
 
 RUST_CLI_LINK_TARGETS_32 := fullbench32 fuzzer32 zstreamtest32