[1.0.28] Fix more cppcheck defects

[1.0.28] Fix more cppcheck defects

- style: C-style pointer casting [cstyleCast]
- style: Parameter 'item' can be declared as reference to const [constParameterReference]
- performance: Function parameter 'mime' should be passed by const reference. [passedByValue]
- performance: Variable '_dirPath' is assigned in constructor body.
               Consider performing initialization in initialization list. [useInitializationList]
- style: The scope of the variable 'ipAddr' can be reduced. [variableScope]
- style: The scope of the variable 'portNum' can be reduced. [variableScope]
- style: inconclusive: Technically the member function 'EsStreamReader::getMediaFormat' can be const. [functionConst]

In addition, a little minor refactoring of MediaTransporterSenderRtsp::startRtspServer()

Change-Id: Ie4d2bfa4275b57947a768c60381bd2dc74985a5d