Introduce DefensiveMin and DefensiveMax (#12554)

* traits for defensive min and defensive max

* defensive min and strict min with tests

* defensive max and strict max with tests

* include docs

* implement partial ord on defensive min and max

* Update frame/support/src/traits/misc.rs

Co-authored-by: Oliver Tale-Yazdi <[email protected]>

* wrap lines

* Fix traits

Signed-off-by: Oliver Tale-Yazdi <[email protected]>

* Update frame/support/src/traits/misc.rs

* Update frame/support/src/traits/misc.rs

Signed-off-by: Oliver Tale-Yazdi <[email protected]>
Co-authored-by: Oliver Tale-Yazdi <[email protected]>
Co-authored-by: parity-processbot <>