refactor: clean up init script

[magdziarek]

• [X] Tests written and linted
• [X] Documentation written
• [X] Commit history is tidy

What this does

Clean up the init script:

• Extract resolving configurations to a function.
• We have removed support for gradle v < 3 so we don't need the special case for these versions.
• Extract code common for both tasks (for snykResolvedDepsJson and snykNormalizedResolvedDepsJson)

[ghost]

This PR modifies files linked to issues tracked in Stepsize. You might want to review their status, priority, and scope.

Use Lenient Configuration by default

- `lib/init.gradle`

✅  extract to a common function

- ✅  ~`lib/init.gradle`~

_{Mention [stepsize] in a comment if you'd like to report some technical debt. See examples here.}

[ghost]

Well done 🎉 You've resolved 1 issue and 1 individual piece of code!

✅  extract to a common function

- ✅  ~`lib/init.gradle`~

[snyksec]

:tada: This PR is included in version 3.25.0 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: