Facilitate way to open an account (in Fava view) from an editor opened on a beancount file.

[seltzered]

Feature Description:

A user should be able to easily transition from editing an account in the text editor to opening fava to see the account (to see transactions, balance, etc.)

The steps should be akin to:

1. User opens beancount file in editor
2. On text representing an account (e.g. Liabilities:CreditCard) user can either 'ctrl+click' to open in fava, or right-click to bring up a menu with an 'Open Account in Fava' option.

This may need to be implemented via a fork of https://github.com/Lencerf/vscode-beancount