Validate input of JNI::NewStringUTF().

Do a minimal validation needed to construct valid strings.
If the validation fails, replace invalid sequences with '?'.

Test: Additional tests in JniInternalTest.NewStringUTF
Test: m test-art-host-gtest
Bug: 172655291
Merged-In: Ica2c5c33f981cbd2f07e7990b3e321cd3b7473b6
Change-Id: Ica2c5c33f981cbd2f07e7990b3e321cd3b7473b6
(cherry picked from commit 7430d794873786e57d5475de41959f5b1b7a8288)