BCLXML doesn't handle AttributeVector

Issue overview

OpenStudio::Attribute has an AttributeVector value type, but it is not supported by BCLXML.

Current Behavior

No warning is issued, but it is not serialized in saving. Nor would it be read.

https://github.com/NREL/OpenStudio/blob/4303dda75d9f59da5e4bd51974410263444bb5a5/src/utilities/bcl/BCLXML.cpp#L687-L690

Expected Behavior

We should implement support for it, or warn when you try to add an AttributeVector in BCLXML::addAttribute.

Steps to Reproduce

bclXML = OpenStudio::BCLXML.new('measure.xml')

consideration1 = OpenStudio::Attribute.new("consideration", "Check transformer capacity when installing a heat pump.")
consideration2 = OpenStudio::Attribute.new("consideration", "Verify wiring compliance with local electrical codes before installation.")
implementation_considerations = OpenStudio::Attribute.new("implementation_considerations", [consideration1, consideration2])

n = bclXML.attributes.size

# The bclXML has the new attribute, but it will NOT be serialized to measure.xml when you save, nor in puts
bclXML.addAttribute(implementation_considerations)
raise unless bclXML.attributes.size == n + 1
puts bclXML

  <attributes>
    <attribute>
      <name>Measure Type</name>
      <value>ModelMeasure</value>
      <datatype>string</datatype>
    </attribute>
    <attribute>
      <name>Measure Language</name>
      <value>Ruby</value>
      <datatype>string</datatype>
    </attribute>
-   <attribute>
-      <name>string_attribute</name>
-      <datatype>AttributeVector<datatype>
-         <value>
-            <attributes>...</attributes>
-         </value>
-    </attribute>
  </attributes>

Details

Environment

Some additional details about your environment for this issue (if relevant):

• Platform (Operating system, version): All
• Version of OpenStudio (if using an intermediate build, include SHA): 3.10.0-alpha

Context

Just realized this after trying to add nested attributes in measure.xml

Start in src/utilities/bcl/BCLXML.cpp around lines 687-690 and inspect BCLXML::addAttribute, using the Ruby reproduction with measure.xml as the first check. Trace how existing attribute types are serialized and read. Done means AttributeVector is handled consistently, or addAttribute clearly warns when it is unsupported, with the reproduction no longer silently losing the attribute.