[llvm] [llvm/CAS] Add file-based APIs to `ObjectStore` (PR #180657)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-solaris11-sparcv9` running on `solaris11-sparcv9` while building `llvm` at step 5 "ninja check 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/13/builds/11769

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 5 (ninja check 1) failure: stage 1 checked (failure)
...
[1297/1370] Linking CXX executable bin/OrcV2CBindingsBasicUsage
[1298/1370] Linking CXX executable bin/OrcV2CBindingsRemovableCode
[1299/1370] Linking CXX executable unittests/ADT/ADTTests
[1300/1370] Linking CXX executable bin/OrcV2CBindingsLazy
[1301/1370] Linking CXX executable unittests/AsmParser/AsmParserTests
[1302/1370] Linking CXX executable unittests/BinaryFormat/BinaryFormatTests
[1303/1370] Linking CXX executable bin/LLJITWithRemoteDebugging
[1304/1370] Linking CXX executable unittests/Bitstream/BitstreamTests
[1305/1370] Linking CXX executable bin/OrcV2CBindingsVeryLazy
[1306/1370] Linking CXX executable unittests/CAS/CASTests
FAILED: unittests/CAS/CASTests 
: && /opt/llvm/22/bin/clang++ -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wno-pass-failed -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections  -O -DNDEBUG -Wl,-z,discard-unused=sections unittests/CAS/CMakeFiles/CASTests.dir/ActionCacheTest.cpp.o unittests/CAS/CMakeFiles/CASTests.dir/CASTestConfig.cpp.o unittests/CAS/CMakeFiles/CASTests.dir/NamedValuesSchemaTest.cpp.o unittests/CAS/CMakeFiles/CASTests.dir/ObjectStoreTest.cpp.o -o unittests/CAS/CASTests  lib/libLLVMSupport.a  lib/libLLVMCAS.a  lib/libLLVMTestingSupport.a  lib/libLLVMSupport.a  lib/libllvm_gtest_main.a  lib/libllvm_gtest.a  lib/libLLVMTestingSupport.a  lib/libllvm_gtest.a  lib/libLLVMSupport.a  -lrt  -ldl  -lm  -lkstat  -lsocket  /usr/lib/64/libz.so  /usr/lib/64/libzstd.so  lib/libLLVMDemangle.a  -lpthread && :
Undefined			first referenced
 symbol  			    in file
_ZN4llvm8unittest3cas15createSmallFileEc unittests/CAS/CMakeFiles/CASTests.dir/ObjectStoreTest.cpp.o
_ZN4llvm8unittest3cas15createLargeFileEc unittests/CAS/CMakeFiles/CASTests.dir/ObjectStoreTest.cpp.o
_ZN4llvm8unittest3cas26createLargePageAlignedFileEc unittests/CAS/CMakeFiles/CASTests.dir/ObjectStoreTest.cpp.o
ld: fatal: symbol referencing errors
clang++: error: linker command failed with exit code 1 (use -v to see invocation)
[1307/1370] Linking CXX executable unittests/CGData/CGDataTests
[1308/1370] Linking CXX executable unittests/Bitcode/BitcodeTests
[1309/1370] Linking CXX executable unittests/Analysis/AnalysisTests
ninja: build stopped: subcommand failed.

```

</details>

https://github.com/llvm/llvm-project/pull/180657