feat: add extension-settings vue component (#2004)

- adds lnbits-extension-settings-form. which is just the plain form of the settings component.
- adds lnbits-extension-settings-btn-dialog. which is the form wrapped into a dialog with a cog button.

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Co-authored-by: Vlad Stan <stan.v.vlad@gmail.com>

lnbits/static/js/service-worker.js

@@ -1,6 +1,6 @@
 // update cache version every time there is a new deployment
 // so the service worker reinitializes the cache
-const CACHE_VERSION = 66
+const CACHE_VERSION = 67
 const CURRENT_CACHE = `lnbits-${CACHE_VERSION}-`
 
 const getApiKey = request => {