Support build-ids of other sizes than 16 in UUID::SetFromStringRef

SBTarget::AddModule currently handles the UUID parameter in a very
weird way: UUIDs with more than 16 bytes are trimmed to 16 bytes. On
the other hand, shorter-than-16-bytes UUIDs are completely ignored. In
this patch, we change the parsing code to handle UUIDs of arbitrary
size.

To support arbitrary size UUIDs in SBTarget::AddModule, this patch
changes UUID::SetFromStringRef to parse UUIDs of arbitrary length. We
subtly change the semantics of SetFromStringRef - SetFromStringRef now
only succeeds if the entire input is consumed to prevent some
prefix-parsing confusion. This is up for discussion, but I believe
this is more consistent - we always return false for invalid UUIDs
rather than sometimes truncating to a valid prefix. Also, all the
call-sites except the API and interpreter seem to expect to consume
the entire input.

This also adds tests for adding existing modules 4-, 16-, and 20-byte
build-ids. Finally, we took the liberty of testing the minidump
scenario we care about - removing placeholder module from minidump and
replacing it with the real module.

Reviewed By: labath, friss

Differential Revision: https://reviews.llvm.org/D80755

lldb/unittests/Target/ModuleCacheTest.cpp

@@ -41,7 +41,6 @@ static const char dummy_remote_dir[] = "bin";
 static const char module_name[] = "TestModule.so";
 static const char module_uuid[] =
     "F4E7E991-9B61-6AD4-0073-561AC3D9FA10-C043A476";
-static const uint32_t uuid_bytes = 20;
 static const size_t module_size = 5602;
 
 static FileSpec GetDummyRemotePath() {
@@ -87,7 +86,7 @@ void ModuleCacheTest::TryGetAndPut(const FileSpec &cache_dir,
   ModuleCache mc;
   ModuleSpec module_spec;
   module_spec.GetFileSpec() = GetDummyRemotePath();
-  module_spec.GetUUID().SetFromStringRef(module_uuid, uuid_bytes);
+  module_spec.GetUUID().SetFromStringRef(module_uuid);
   module_spec.SetObjectSize(module_size);
   ModuleSP module_sp;
   bool did_create;