Remove Hard Coding for Focus Karma Costs

[Teksura]

Is your feature request related to a problem? Please describe.
Presently, Focus Karma Costs are hard coded and set in the settings file. This is actually kind of obnoxious, as it makes it difficult to add new Foci.

Describe the solution you'd like
I'd like to be able to set something in the XML akin to the following:

    <gear>
      <id>62bfb38d-5515-440b-83ed-289ed926d27e</id>
      <name>Power Focus</name>
      <category>Foci</category>
      <rating>18</rating>
      <source>SR5</source>
      <page>319</page>
      <avail>(Rating * 4)R</avail>
      <bonus>
        <skillattribute precedence="0">
          <name>MAG</name>
          <bonus>Rating</bonus>
        </skillattribute>
        <selecttradition />
      </bonus>
      <cost>Rating * 18000</cost>
      <boundfocicost>Rating * 6</boundfocicost>
    </gear>

The presence of <boundfocicost> indicates that the Gear should be treated as a Foci, and that it should be possible to bind. This removes Foci from being hard coded and instead allows technically any gear to be treated as a Foci. This allows a larger range of customization for Foci costs and makes it significantly easier to create custom foci.

[Teksura]

And incidentally, this also works with Individualized foci by just doing a little math:

<boundfocicost>(Rating * 6) - 2</boundfocicost>

which means those won't need hard coded, either.

[Teksura]

Having thought about it a bit more, it might be useful to also leave room to add Plugins which also have a karma cost (especially one which can take the cost from the parent) such as an Imbue Item case.

I can handle all the XML side of it if the C# is done by someone who knows C#

[chummer5a]

Implemented in
https://github.com/chummer5a/chummer5a/tree/feature/focuskarmacost
Weapon focus would be
(({Rating} * 3) * {karmabindmultiplier}) + {karmabindextracost}
where
{Rating} == focus rating
{karmabindmultiplier} == multiplier provided by improvements
{karmabindextracost} == karma point values added/removed by improvements

Also added addimprovementsoncreate to the bonus node which prevents the bonus node from adding improvements when the object is created, we currently use categories for that.