Opt spec app defs and base classes

[cmmngr]

App Defs:

• NXellipsometry(NXopt)
• NXopt

Base classes:

• NXbeam_path
• NXopt_element
• NXbeam_splitter
• NXfiber
• NXlens_opt
• NXpolarizer_opt
• NXwaveplate

[prjemian]

Many errors in CI due to NXDL syntax. Among these:

• E lxml.etree.DocumentInvalid: Element '{http://definition.nexusformat.org/nxdl/3.1}field', attribute 'required': The attribute 'required' is not allowed., line 50
• E Exception: Too many doc elements: line 26, NXlens_opt.nxdl.xml

See: https://pipelines.actions.githubusercontent.com/serviceHosts/450b0598-1549-4d8a-b222-20c2cf327859/_apis/pipelines/1/runs/1080/signedlogcontent/2?urlExpires=2023-05-30T14%3A28%3A13.6751717Z&urlSigningMethod=HMACV1&urlSignature=QKq4zK3g8YPqFSGqqIhmHBWHqZUoV40VjIN%2B1daA7VU%3D

[prjemian]

Too bad the many exceptions do not indicate which NXDL file and line triggered each problem.