bootz skip ownership check

[xw-g]

Add the support of skipping ownership validation in Bootz.

There are 3 sequentially dependent PRs to introduce this changes.

1. Bootz API PR updates Bootz API and README.
2. [This PR] OC modeling PR updates Bootz OpenConfig modeling.
3. FP test PR updates feature profile tests

module: openconfig-system-bootz

  augment /oc-sys:system:
    +--rw bootz
       +--rw config
       |  +--rw validate-ownership?   boolean <<<<<<<<<<<<<<<<<< new
       +--ro state
          +--ro checksum?              string
          +--ro error-count?           oc-yang:counter64
          +--ro status?                enumeration
          +--ro last-boot-attempt?     oc-types:timeticks64
          +--ro ownership-validated?   boolean <<<<<<<<<<<<<<<<<< new
          +--ro validate-ownership?    boolean <<<<<<<<<<<<<<<<<< new

[OpenConfigBot]

Major YANG version changes in commit 4d008986b9c341a7ffe934dd155c11b23ff1b22a: