Fix security vulnerabilities in PduParser.java

- Fix ArrayIndexOutOfBoundsException in parseContentType by adding bounds check for PduContentTypes.contentTypes index.
- Fix NullPointerExceptions in parseContentTypeParams by adding null checks for map and charsetStr.

Bug: 513582756
Test: TelephonyCommonTests (PduParserTest)
Flag: EXEMPT BUGFIX
(cherry picked from commit cbb0d81bf0866a8249eca7c7ec53f7c179f8b171)
Cherrypick-From: https://googleplex-android-review.googlesource.com/q/commit:6c0911eb7e0128b1a8b13b51378e268618a0305b
Merged-In: I4fab1579d22c4a1dcf2d75d4f4aab0a352df1bd9
Change-Id: I4fab1579d22c4a1dcf2d75d4f4aab0a352df1bd9