[yaml2obj] - Add a way to override the sh_addralign field of a section.

Imagine the following declaration of a section:
```
Sections:
  - Name:         .dynsym
    Type:         SHT_DYNSYM
    AddressAlign: 0x1111111111111111
```

The aligment is large and yaml2obj reports an error currently:
"the desired output size is greater than permitted. Use the --max-size option to change the limit"

This patch implements the "ShAddrAlign" key, which is similar to other "Sh*" keys we have.
With it it is possible to override the `sh_addralign` field, ignoring the writing of alignment bytes.

Differential revision: https://reviews.llvm.org/D90019