client-sdk: add OmniAccount helpers #8721

Job	Run time
sequentialise	3s
fmt	1m 18s
set-condition	12s
tee-check	26m 4s
identity-build	2m 15s
omni-executor-check	4s
parachain-build-dev	7m 8s
bitacross-build	3m 31s
parachain-clippy	0s
parachain-runtime-test	0s
parachain-unit-test	0s
lit-sign-bitcoin	4m 12s
litentry	2m 23s
lit-di-identity-test	5m 2s
rococo	1m 26s
lit-dr-vc-test	4m 2s
paseo	2m 19s
${{ matrix.test_name }}	0s
lit-parentchain-nonce	5m 2s
lit-test-failed-parentchain-extrinsic	3m 58s
push-docker	0s
	1h 8m 59s

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