test: simplify symbolic tests using new halmos cheatcode

[daejunpark]

[this is a temporary pr to be upstreamed after halmos v2 is released.]

this pr improves symbolic tests using new halmos cheatcode createCalldata().

previously, symbolic tests required custom calldata generators to handle dynamic size arrays and bytes. the new createCalldata() cheatcode now seamlessly supports such dynamically-sized parameters by considering all combinations of size candidates. these can be specified using additional flags --array-lengths and --default-bytes-lengths (see halmos -h for more details.)

with this new cheatcode, the symbolic tests are now much simpler to understand and maintain, while also accounting for more combinations of dynamic parameter sizes.

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PR-Codex overview

The focus of this PR is to refactor the check_Invariants_PostMigration function and remove unnecessary code in IdRegistrySymTest.

Detailed summary

• Refactored check_Invariants_PostMigration function in IdRegistrySymTest
• Removed _calldataFor function from IdRegistrySymTest
• Updated check_Invariants function in KeyRegistrySymTest to use svm.createCalldata
• Removed split_cases and mk_calldata functions from KeyRegistrySymTest
• Added slice function to KeyRegistrySymTest

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[daejunpark]

wrong base repo, close for now.