Writing tests for the entrypoints

The branch https://github.com/marigold-dev/checker-ligo/tree/test-entrypoints tries to test Checker entrypoints, but this fails due to some limitations of the compiler:
* we can't serialize the entrypoints as we do in “release mode” (https://github.com/marigold-dev/checker-ligo/blob/test-entrypoints/checker_tools/client/compilation.py#L139);
* a solution to the previous problem is to not serialize them [and call them directly](https://github.com/marigold-dev/checker-ligo/blob/test-entrypoints/src/checkerMainTest.mligo#L6); unfortunately (but predictably) this fails because the resulting contract is too big, forcing us to change at least some constants in the compiler [as we had to do to allow parallel compilation](https://github.com/marigold-dev/checker-ligo/issues/1#issuecomment-1517880045).

This is blocking at the moment.

Review the test-entrypoints branch, especially checker_tools/client/compilation.py near line 139 and src/checkerMainTest.mligo near line 6. Check the compiler constants discussed in issue #1 and determine how entrypoint tests can run within serialization and contract-size limits. Done means the entrypoints have automated tests that pass without the current compiler limitations blocking them.

Written by the indexing model from the issue text.