Add gtest TCs for cache APIs

Add gtest TCs for cache APIs

[   29s] [ RUN      ] DownloadTest.SetCacheP
[   29s] [       OK ] DownloadTest.SetCacheP (0 ms)
[   29s] [ RUN      ] DownloadTest.GetCacheN
[   29s] [       OK ] DownloadTest.GetCacheN (0 ms)
[   29s] [ RUN      ] DownloadTest.GetCacheP
[   29s] [       OK ] DownloadTest.GetCacheP (0 ms)
[   29s] [ RUN      ] DownloadTest.ResetCacheP
[   29s] [       OK ] DownloadTest.ResetCacheP (0 ms)
[   29s] [ RUN      ] DownloadTest.GetCacheMaxSizeN
[   29s] [       OK ] DownloadTest.GetCacheMaxSizeN (0 ms)
[   29s] [ RUN      ] DownloadTest.GetCacheMaxSizeP
[   29s] [       OK ] DownloadTest.GetCacheMaxSizeP (0 ms)
[   29s] [ RUN      ] DownloadTest.SetCacheMaxSizeP
[   29s] [       OK ] DownloadTest.SetCacheMaxSizeP (0 ms)
[   29s] [ RUN      ] DownloadTest.ResetAllCacheP
[   29s] [       OK ] DownloadTest.ResetAllCacheP (0 ms)
[   29s] [ RUN      ] DownloadTest.GetCachePathN
[   29s] [       OK ] DownloadTest.GetCachePathN (0 ms)
[   29s] [ RUN      ] DownloadTest.GetCachePathP
[   29s] [       OK ] DownloadTest.GetCachePathP (0 ms)
[   29s] [ RUN      ] DownloadTest.SetCachePathP
[   29s] [       OK ] DownloadTest.SetCachePathP (0 ms)
[   29s] [ RUN      ] DownloadTest.GetCacheLifecycleN
[   29s] [       OK ] DownloadTest.GetCacheLifecycleN (0 ms)
[   29s] [ RUN      ] DownloadTest.GetCacheLifecycleP
[   29s] [       OK ] DownloadTest.GetCacheLifecycleP (0 ms)
[   29s] [ RUN      ] DownloadTest.SetCacheLifecycleP
[   29s] [       OK ] DownloadTest.SetCacheLifecycleP (0 ms)

Change-Id: I4fddf9a326a7dc7a0036a36ecc2ea51ff9aec39d
Signed-off-by: Jaehyun Kim <jeik01.kim@samsung.com>