sound: Support multi-theme sound conf usage

sound: Support multi-theme sound conf usage

Allows users to select one of several theme files.
Conf file detailed usage is explained in the common/data/sound.conf file.

Example of conf file usage
[SoundMultiTheme] -> It means support multi theme
number_of_theme=2 -> It means how many confs are supported
name_of_default_theme=SoundTheme2 -> It means SoundTheme2 section file is set to default conf
[SoundTheme1] -> Match the conf file number and file path
file_path_of_theme=/usr/share/feedback/sound-theme1.conf
[SoundTheme2]
file_path_of_theme=/usr/share/feedback/sound-theme2.conf

To support this, below functions are newly added to feedback-internal.h.
- int feedback_get_count_of_theme_internal(feedback_type_e feedback_type, unsigned int *count_of_theme);
    - This function gets the number of theme described in the config file.
- int feedback_get_theme_index_internal(feedback_type_e feedback_type, unsigned int *index_of_theme);
    - This function gets the current index of theme selected.
- int feedback_set_theme_index_internal(feedback_type_e feedback_type, unsigned int index_of_theme);
    - This function sets the index of theme will be used.
      After that, It is possible to use the feedback files defined in the theme(index_of_theme) conf file.

In deed, this patch only supports sound theme.

Change-Id: Idd25bed7b091fffe6d9c7a5729a670f0f27469c4
Signed-off-by: Yunhee Seo <yuni.seo@samsung.com>