add Background Fetch method #13191

Job	Run time
cargo deny	33s
Lint Rust	5m 31s
Check provider database	6s
Rust doc comments	3m 3s
Rust tests (ubuntu-latest, 1.74.1)	8m 2s
Build C library (ubuntu-latest)	7m 0s
Rust tests (windows-latest, 1.74.1)	19m 45s
Build deltachat-rpc-server (ubuntu-latest)	6m 43s
Build C library (macos-latest)	3m 59s
Python lint	10s
Rust tests (macos-latest, 1.74.1)	6m 33s
Build deltachat-rpc-server (macos-latest)	11m 9s
Build deltachat-rpc-server (windows-latest)	17m 52s
Rust tests (ubuntu-latest, 1.70.0)	8m 27s
CFFI Python tests	0s
JSON-RPC Python tests	0s
	1h 38m 53s

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