[Biobank] Include Visit Label in Specimen Entity

[HenriRabalais]

Summary

Fixes a front-end crash when viewing a specimen whose collection session is
at a site the user doesn't have access to. The specimen is visible (the user
has access to its container site), but its session is correctly never
provisioned to the front end. The front end then tried to look up the session
label in options.sessions and read .label off undefined, throwing.

The fix provisions the session's visit label directly onto the specimen
entity, so the label can be displayed without depending on the
access-filtered session options. The hyperlink to the session is now rendered
only when the session is present in options.sessions (i.e. the user can
access it); otherwise the visit label is shown as plain text.

Changes

• specimendao.class.inc: Added s.Visit_label as SessionLabel to the
  existing session join in the specimen select, and set it on the specimen in
  _getInstanceFromSQL.
• specimen.class.inc: Added a sessionLabel property with
  setter/getter, and included it in jsonSerialize.
• <display view file>: Read the visit label from specimen.sessionLabel
  instead of options.sessions[sessionId].label, and made the session link
  conditional on the session being present in options.sessions.
• specimenForm.js: Carried sessionLabel across from the parent
  specimen in componentDidUpdate, and read the label from current instead
  of options.sessions in renderGlobalFields.