Add Flystem Cells

[Jannetty]

Note: Please review #218 and #219 before reviewing this PR. This branch includes those changes, so they should be merged into main first. Once that happens, the diff in this PR will be significantly smaller.

Estimated time to review: Large (sorry)

Summary of changes:
This code adds the fly neuroblast code into the codebase. The changes include:

• Adding fly stem cell classes to the potts cell container convert method so convert can call the PottsCellFlyStem constructor when the stem cell classes are specified in the constructor.
• Adding PottsCellFlyStem class (and test class)
• Adding PottsCellFlyStemProliferation module which includes all plane of division logic, growth rate regulation logic, differentiation logic (and tests)
• Made getUniqueIDs a public function for all implementations so that the PottsCellFlyStemProliferation module can use it to determine the identities of neighboring cells
• Adding parameters needed for PottsCellFlyStem and PottsCellFlyStemProliferationModule

How to verify changes:

• run tests
• Here is a minimal neuroblast setup file which you can run on this branch:

<set prefix="2025-10-23-01">
    <series name="dd" start="1" end="1"
            ds=".3" margin="0" height="1" length="802" width="802"
            dt=".083" ticks="576" interval="4">
        <potts>
            <potts.term id="volume" />
            <potts.term id="adhesion" />
            <potts.term id="surface" />
        </potts>
        <agents>
            <populations>
                <population id="fly-stem-wt" class="fly-stem-wt" init="1" >
                    <population.link id="fly-gmc" weight="1"/>
                    <population.parameter id="proliferation/SIZE_TARGET" value="1.2" />
                    <population.parameter id="CRITICAL_VOLUME" value="52" units="um^3" conversion="DS^-3" />
                    <population.parameter id="proliferation/CELL_GROWTH_RATE" value="5" units="um^3/hour" conversion="DS^-3DT"/>
                    <population.parameter id="proliferation/BASAL_APOPTOSIS_RATE" value="0"/>
                    <population.parameter id="proliferation/DIV_ROTATION_DISTRIBUTION" value="NORMAL(MU=36,SIGMA=30)" />
                    <population.parameter id="proliferation/DIFFERENTIATION_RULESET" value="location" />
                    <population.parameter id="proliferation/DIFFERENTIATION_RULESET_EQUALITY_RANGE" value="10" />
                    <population.parameter id="proliferation/APICAL_AXIS_RULESET" value="uniform" />
                    <population.parameter id="proliferation/APICAL_AXIS_ROTATION_DISTRIBUTION" value="UNIFORM(MIN=0,MAX=360)" />
                    <population.parameter id= "proliferation/DYNAMIC_GROWTH_RATE_VOLUME" value="0" />
                    <population.parameter id= "proliferation/DYNAMIC_GROWTH_RATE_NB_CONTACT" value="0" />
                    <population.parameter id= "proliferation/VOLUME_BASED_CRITICAL_VOLUME" value="1" />
                </population>
                <population id="fly-gmc" class="fly-gmc" init="0">
                 <population.link id="fly-neuron" weight="1"/>
                 <population.parameter id="proliferation/BASAL_APOPTOSIS_RATE" value="0"/>
                 <population.parameter id="CRITICAL_VOLUME" value="11" units="um^3" conversion="DS^-3" />
                 <population.parameter id="proliferation/CELL_GROWTH_RATE" value="1.22" units="um^2/hour" conversion="DS^-2.DT"/>
                 <population.parameter id= "proliferation/DYNAMIC_GROWTH_RATE_VOLUME" value="0" />
                </population>
                <population id="fly-neuron" class="fly-neuron" init="0">
                <population.parameter id="proliferation/CELL_GROWTH_RATE" value="0"/>
                <population.parameter id="proliferation/BASAL_APOPTOSIS_RATE" value="0"/>
                <population.parameter id="CRITICAL_VOLUME" value="11" units="um^3" conversion="DS^-3" />
                </population>
            </populations>
        </agents>
    </series>
</set>

resolves #137
resolves #109
resolves #91
resolves #58
resolves #50

[Jannetty]

Make clear in documentation that these values are the named variables below