Add IRPGO and CSIRPGO options to Swift (#84335)

This PR introduces three new instrumentation flags and plumbs them
through to IRGen:

1. `-ir-profile-generate` - enable IR-level instrumentation.
2. `-cs-profile-generate` - enable context-sensitive IR-level
instrumentation.
3. `-ir-profile-use` - IR-level PGO input profdata file to enable
profile-guided optimization (both IRPGO and CSIRPGO)

**Context:**
https://forums.swift.org/t/ir-level-pgo-instrumentation-in-swift/82123

**Swift-driver PR:** https://github.com/swiftlang/swift-driver/pull/1992

**Tests and validation:**
This PR includes ir level verification tests, also checks few edge-cases
when `-ir-profile-use` supplied profile is either missing or is an
invalid IR profile.

However, for argument validation, linking, and generating IR profiles
that can later be consumed by -cs-profile-generate, I’ll need
corresponding swift-driver changes. Those changes are being tracked in
https://github.com/swiftlang/swift-driver/pull/1992

lib/Driver/UnixToolChains.cpp

@@ -40,6 +40,7 @@
 using namespace swift;
 using namespace swift::driver;
 using namespace llvm::opt;
+using namespace swift::driver::toolchains;
 
 std::string
 toolchains::GenericUnix::sanitizerRuntimeLibName(StringRef Sanitizer,
@@ -330,7 +331,7 @@ toolchains::GenericUnix::constructInvocation(const DynamicLinkJobAction &job,
     }
   }
 
-  if (context.Args.hasArg(options::OPT_profile_generate)) {
+  if (needsInstrProfileRuntime(context.Args)) {
     SmallString<128> LibProfile(SharedResourceDirPath);
     llvm::sys::path::remove_filename(LibProfile); // remove platform name
     llvm::sys::path::append(LibProfile, "clang", "lib");