[yaml2obj] - Support reading a content as an array of bytes using the new 'ContentArray' key.
It implements the way to describe a section content using a multi line description. E.g:
```
- Name: .foo
Type: SHT_PROGBITS
ContentArray: [ 0x11, 0x22, 0x33, 0x44, ## .long
11223344
0x55, 0x66, ## .short 5566.
0x77, ## .byte 0x77
0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF, 0x00 ] ## .quad 0x8899aabbccddeeff
```
It was briefly discussed in D75123 thread previously.
Differential revision: https://reviews.llvm.org/D82366