Partition table JSON boolean flag values are ignored

The actual values of the `no_reboot_on_uf2_download`, `ab_non_bootable_owner_affinity`, `ignored_during_riscv_boot`, and `ignored_during_arm_boot` in a partition table's JSON are ignored by `picotool`. 

For example 

```json
"ignored_during_arm_boot": false,
"ignored_during_riscv_boot": true
```

ignores **_both_** ARM and RISC-V.