[llvm] [MIR2Vec] Add embedder for machine instructions (PR #162161)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-aarch64-darwin` running on `doug-worker-4` while building `llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/190/builds/29470

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

```
Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'LLVM-Unit :: CodeGen/./CodeGenTests/0/19' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/Volumes/RAMDisk/buildbot-root/aarch64-darwin/build/unittests/CodeGen/./CodeGenTests-LLVM-Unit-69057-0-19.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=19 GTEST_SHARD_INDEX=0 /Volumes/RAMDisk/buildbot-root/aarch64-darwin/build/unittests/CodeGen/./CodeGenTests
--

Note: This is test shard 1 of 19.
[==========] Running 16 tests from 15 test suites.
[----------] Global test environment set-up.
[----------] 1 test from AllocationOrderTest
[ RUN      ] AllocationOrderTest.Basic
[       OK ] AllocationOrderTest.Basic (0 ms)
[----------] 1 test from AllocationOrderTest (0 ms total)

[----------] 1 test from AsmPrinterEmitDwarfStringOffsetTest
[ RUN      ] AsmPrinterEmitDwarfStringOffsetTest.DWARF64
/Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/llvm/unittests/CodeGen/AsmPrinterDwarfTest.cpp:180: Skipped


[  SKIPPED ] AsmPrinterEmitDwarfStringOffsetTest.DWARF64 (0 ms)
[----------] 1 test from AsmPrinterEmitDwarfStringOffsetTest (0 ms total)

[----------] 1 test from DIEHashTest
[ RUN      ] DIEHashTest.ReusedType
[       OK ] DIEHashTest.ReusedType (0 ms)
[----------] 1 test from DIEHashTest (0 ms total)

[----------] 1 test from DroppedVariableStatsMIR
[ RUN      ] DroppedVariableStatsMIR.InlinedAtShared
[       OK ] DroppedVariableStatsMIR.InlinedAtShared (6 ms)
[----------] 1 test from DroppedVariableStatsMIR (6 ms total)

[----------] 1 test from InstrRefLDVTest
[ RUN      ] InstrRefLDVTest.pickVPHILocBadlyNestedLoops
/Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/llvm/unittests/CodeGen/InstrRefLDVTest.cpp:81: Skipped


[  SKIPPED ] InstrRefLDVTest.pickVPHILocBadlyNestedLoops (0 ms)
[----------] 1 test from InstrRefLDVTest (0 ms total)

[----------] 1 test from LowLevelTypeTest
[ RUN      ] LowLevelTypeTest.ConstExpr
[       OK ] LowLevelTypeTest.ConstExpr (0 ms)
[----------] 1 test from LowLevelTypeTest (0 ms total)

[----------] 1 test from IsIdenticalToTest
[ RUN      ] IsIdenticalToTest.DifferentDefs
[       OK ] IsIdenticalToTest.DifferentDefs (0 ms)
[----------] 1 test from IsIdenticalToTest (0 ms total)

...

```

</details>

https://github.com/llvm/llvm-project/pull/162161