NXsas: review use of minOccurs on various components

[prjemian]

nexusformat/definitions#522

[prjemian]

Not ready for NIAC consideration yet.

[prjemian]

There is no PR for this issue at this time. The issue (in definitions repo) was posted 5 years ago. It is possible that some community discussion needed to make a new PR ready. I suggest we move this issue to the next NIAC meeting (later in 2022).

[prjemian]

NIAC2022: Still no branch & PR

[benajamin]

Proposal is to accept the changes to NXsas in pull request nexusformat/definitions#1194