Allow implicit conversions for NN errors -- hal

This change allows GeneralErrors to be created from a string and allows
ExecutionErrors to be created from a string or a GeneralError.
This makes error handling more terse, removing the need for helper
functions such as makeGeneralFailure or makeExecutionFailure.

Bug: N/A
Test: mma
Change-Id: I8c5e80a2eb4f399fad64aab763fe6fa08cf8d1db
diff --git a/neuralnetworks/1.0/utils/src/PreparedModel.cpp b/neuralnetworks/1.0/utils/src/PreparedModel.cpp
index 00970c0..3060c65 100644
--- a/neuralnetworks/1.0/utils/src/PreparedModel.cpp
+++ b/neuralnetworks/1.0/utils/src/PreparedModel.cpp
@@ -63,12 +63,11 @@
     // Ensure that request is ready for IPC.
     std::optional<nn::Request> maybeRequestInShared;
     hal::utils::RequestRelocation relocation;
-    const nn::Request& requestInShared =
-            NN_TRY(hal::utils::makeExecutionFailure(hal::utils::convertRequestFromPointerToShared(
-                    &request, nn::kDefaultRequestMemoryAlignment, nn::kMinMemoryPadding,
-                    &maybeRequestInShared, &relocation)));
+    const nn::Request& requestInShared = NN_TRY(hal::utils::convertRequestFromPointerToShared(
+            &request, nn::kDefaultRequestMemoryAlignment, nn::kMinMemoryPadding,
+            &maybeRequestInShared, &relocation));
 
-    const auto hidlRequest = NN_TRY(hal::utils::makeExecutionFailure(convert(requestInShared)));
+    const auto hidlRequest = NN_TRY(convert(requestInShared));
 
     return executeInternal(hidlRequest, relocation);
 }