Support for greater diversity in valueflag_cd / flagstouse in c_metadataxml

Currently, the webclient seems to only support either:
* flagstouse: A
* flagstouse: HL

with no mixing between sets.

LOINC and HL7 support a much larger set:

User-defined Table 0078 - Abnormal flags
Value Description
L Below low normal
H Above high normal
LL Below lower panic limits
HH Above upper panic limits
< Below absolute low-off instrument scale
> Above absolute high-off instrument scale
N Normal (applies to non-numeric results)
A Abnormal (applies to non-numeric results)
AA Very abnormal (applies to non-numeric units, analogous to panic limits for numeric
units)
U Significant change up
D Significant change down
B Better--use when direction not relevant
W Worse--use when direction not relevant
S Susceptible. Indicates for microbiology susceptibilities only.
R Resistant. Indicates for microbiology susceptibilities only.
I Intermediate. Indicates for microbiology susceptibilities only.
MS Moderately susceptible. Indicates for microbiology susceptibilities only.
VS Very susceptible. Indicates for microbiology susceptibilities only

https://loinc.org/meetings/20050606/public-laboratory-workshop-committee-meeting-06-06-2005/handout_a.pdf

It would be nice to be able to make these as queryable flags as well.