Integrate dbp-provider and AdapterLitElement (#32)

assets/dbp-official-signature-pdf-upload.metadata.json

assets/dbp-qualified-signature-pdf-upload.metadata.json

assets/dbp-signature-verification-full.metadata.json

assets/dbp-signature-verification.metadata.json

assets/dbp-signature.html.ejs

rollup.config.js

src/dbp-official-signature-pdf-upload.js

src/dbp-pdf-preview.js

src/dbp-qualified-signature-pdf-upload.js

src/dbp-signature-lit-element.js

src/dbp-signature-verification-full.js

src/dbp-signature-verification.js

vendor/toolkit

yarn.lock