[llvm] [SandboxIR] Implement BranchInst (PR #100063)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-win-fast` running on `as-builder-3` while building `llvm` at step 7 "test-build-unified-tree-check-llvm-unit".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/2/builds/2919

Here is the relevant piece of the build log for the reference:
```
Step 7 (test-build-unified-tree-check-llvm-unit) failure: test (failure)
******************** TEST 'LLVM-Unit :: SandboxIR/./SandboxIRTests.exe/9/19' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:C:\buildbot\as-builder-3\llvm-clang-x86_64-win-fast\build\unittests\SandboxIR\.\SandboxIRTests.exe-LLVM-Unit-13192-9-19.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=19 GTEST_SHARD_INDEX=9 C:\buildbot\as-builder-3\llvm-clang-x86_64-win-fast\build\unittests\SandboxIR\.\SandboxIRTests.exe
--

Script:
--
C:\buildbot\as-builder-3\llvm-clang-x86_64-win-fast\build\unittests\SandboxIR\.\SandboxIRTests.exe --gtest_filter=SandboxIRTest.BranchInst
--
C:\buildbot\as-builder-3\llvm-clang-x86_64-win-fast\llvm-project\llvm\unittests\SandboxIR\SandboxIRTest.cpp(688): error: Death test: Br->getCondition()
    Result: failed to die.
 Error msg:
[  DEATH   ] 

C:\buildbot\as-builder-3\llvm-clang-x86_64-win-fast\llvm-project\llvm\unittests\SandboxIR\SandboxIRTest.cpp(700): error: Death test: Br->getCondition()
    Result: failed to die.
 Error msg:
[  DEATH   ] 


C:\buildbot\as-builder-3\llvm-clang-x86_64-win-fast\llvm-project\llvm\unittests\SandboxIR\SandboxIRTest.cpp:688
Death test: Br->getCondition()
    Result: failed to die.
 Error msg:
[  DEATH   ] 

C:\buildbot\as-builder-3\llvm-clang-x86_64-win-fast\llvm-project\llvm\unittests\SandboxIR\SandboxIRTest.cpp:700
Death test: Br->getCondition()
    Result: failed to die.
 Error msg:
[  DEATH   ] 



********************


```

https://github.com/llvm/llvm-project/pull/100063