DCC german template with pdf only

[bergmann-dierk]

New Pull Requests with changes concerning PDF DCC generation for CWA users.
DCC Page of PDF is appended after DccUploadResult is received and qrCode string is generated successfully.

Unittest Example:
unittestCert.pdf

[dsarkar]

@bergmann-dierk see issue corona-warn-app/cwa-documentation#644 regarding the format of the template. I think the QR code is now placed away from the border, displayed larger etc.

See also these templates: https://github.com/Digitaler-Impfnachweis/certification-apis/tree/master/templates

In short, to prevent issues regarding QR code scanning, as they were observed already on similar documents, the following has been implemented corona-warn-app/cwa-documentation#644 (comment):

Summary:

1. Position of the QR code is to close to the edge edge of paper -> reposition away from the edge
2. Size of the QR code is too small, see e.g. Suggestion to modify DE EU Digital Covid Vaccination Certificate format cwa-documentation#644 (comment) and Suggestion to modify DE EU Digital Covid Vaccination Certificate format cwa-documentation#644 (comment) -> increase size
3. The QR code should be placed on a white frame, see Suggestion to modify DE EU Digital Covid Vaccination Certificate format cwa-documentation#644 (comment) . (This may be referred to as a margin in some QR code generators.) This might be root cause for paper QR Code not readable cwa-app-android#3514 (comment)
4. High error correction level in the QR code

[vaubaehn]

@dsarkar good catch - thanks that you took care of this!

[dsarkar]

@vaubaehn actually, some credits should go to @Ein-Tim, since he mentioned this PR in our wishlist repository and that's what directed my attention here. So thanks also to @Ein-Tim!