feat(jstzd): add config init for client

[ryutamago]

Context

141

blocked by #572

Description

This PR implements the octez_client config init
In order to be consistent with the api for #582 i return the Child and let the user handle it.
Note: i omitted the following two argumetns as this is only used for mockup mode

--bootstrap-accounts 
--protocol-constants

Manually testing the PR

two integration test:

cargo test --package jstzd --test octez_client_test         

output:

running 2 tests
test command_fails_on_non_utf8_path ... ok
test config_init ... ok

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 3 lines in your changes missing coverage. Please review.

Project coverage is 37.36%. Comparing base (5fb136e) to head (faa2ddb).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/jstzd/src/task/octez_client.rs	66.66%	0 Missing and 3 partials ⚠️

Files with missing lines	Coverage Δ
crates/jstzd/src/task/octez_client.rs	88.65% <66.66%> (+3.79%)	⬆️

... and 1 file with indirect coverage changes

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[huancheng-trili]

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