Validate input of JNI::NewStringUTF().

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

(cherry picked from commit d0b940349294a363e6d578adf58db8222c425669)

Test: Additional tests in JniInternalTest.NewStringUTF
Test: m test-art-host-gtest
Bug: 172655291
Merged-In: I683c142fe5972599297d604f775bb8cfe6154bb7
Merged-In: Ica2c5c33f981cbd2f07e7990b3e321cd3b7473b6
Change-Id: Ieda5a89b738bbb624872512a400855866e120acd