Remove anki.md.insertNewCardID option?

[jasonwilliams]

This comes out of #133
You currentlt need to set both anki.md.updateCards and anki.md.insertNewCardID for persistence, but in the end we only insert new card IDs so it should just be the default anyway. As we don't plan to have any other update mechanism maybe anki.md.updateCards on its own is enough.

This would require changing

anki/src/markdown/transformer.ts

Line 66 in 365843e

if (this.getConfig("insertNewCardID")) {

to be updateCards instead.