Replace char pointer with char array in samples.

[ActoryOu]

Issue #, if available:
#107

Description of changes:
The sample codes for Jobs_StartNextMsg() and Jobs_UpdateMsg() in jobs.h is wrong. Replace the char pointer with char array to calculate the length correctly.

---

For example, before changing:

const char * statusDetails = "{\"key\":\"value\"}";
/* ... */
request.statusDetailsLength = ( sizeof( statusDetails ) - 1U );

In this case, sizeof( statusDetails ) returns the size of pointer, which is 4 or 8, instead of the length.

---

After changing:

const char statusDetails[] = "{\"key\":\"value\"}";
/* ... */
request.statusDetailsLength = ( sizeof( statusDetails ) - 1U );

In this case, sizeof( statusDetails ) returns the size of array, which is 15.

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