Create form component for each header type

[nbintertech]

We need to replace the shared header form component used in steam, with form components for each header type (low, med, high). Shared component worked fine originally, but validation has become complex, the lifecycle/event loop timing is also pretty shakey.

[nbintertech]

Found in #7661 - header form is being initialized in boiler also. Has some suspect/confusing looking logic re: using highest p header form for lowest pressure