Add is_abandoned flag to segments

[brad-richardson]

Description

Adds road flag that allows for identification and downstream filtering of segments that are no longer maintained. These are typically denoted in OSM with abandoned*= and disused*= tags.

Reference

1. Internal issue

Testing

Ran all tests including against added example.

Checklist

1. Add relevant examples.
2. Add relevant counterexamples.
3. Update in-schema documentation using plain English written in complete sentences, if an update is required.
4. Update Docusaurus documentation, if an update is required.
5. Review change with Overture technical writer to ensure any advanced documentation needs will be taken care of, unless the change is trivial and would not affect the documentation.

Documentation Website

Docs preview for this PR.

[jonahadkins]

LGTM 👍

[vcschapp]

                       _____|\
                  _.--| SSt |:
                 <____|.----||
                        .---''---,
                         ;..__..'    _...
                       ,'/  ;|/..--''    \
                     ,'_/.-/':            :
                _..-'''/  /  |  \    \   _|/|
               \      /-./_ \;   \    \,;'   \
               ,\    / \:  `:\    \   //    `:`.
             ,'  \  /-._;   | :    : ::    ,.   .
           ,'     ::   /`-._| |    | || ' :  `.`.)
        _,'       |;._:: |  | |    | `|   :    `'
      ,'   `.     /   |`-:_ ; |    |  |  : \
      `--.   )   /|-._:    :          |   \ \
         /  /   :_|   ;`-._;   __..--';    : :
        /  (    ;|;-./_  _/.-:'o |   /     ' |
       /  , \._/_/_./--''/_|:|___|_,'        |
      :  /   `'-'--'----'---------'          |
      | :     O ._O   O_. O ._O   O_.      ; ;
      : `.      //    //    //    //     ,' /
    ~~~`.______//____//____//____//_______,'~
              //    //~   //    //
       ~~   _//   _//   _// ~ _//     ~
     ~     / /   / /   / /   / /  ~      ~~
          ~~~   ~~~   ~~~   ~~~