ObjectSpace.dump: handle Module#set_temporary_name

[Bug #20892]

Until the introduction of that method, it was impossible for a
Module name not to be valid JSON, hence it wasn't going through
the slower escaping function.

This assumption no longer hold.

Co-authored-by: Jean Boussier <jean.boussier@gmail.com>

Not all `ID` have an associated string.

Fixes a SEGFAULT in ObjectSpace.dump_all spec.

This reverts commit 5f3fb4f4e397735783743fe52a7899b614bece20.

This records the called_id and klass from imemo_callcache objects in
heap dumps.

This reverts commit f6910a61122931e4193bcc0fad18d839c319b720.

We're seeing crashes in the test suite of Shopify's core monolith after
this change.

We don't need to create a shape to transition capacity as we can
transition the capacity when the capacity of the SHAPE_IVAR changes.

This commit makes every initial size pool shape a root shape and assigns
it a capacity of 0.

I don't think it's possible to create a CI with a mid which would need
escaping to be in a JSON string, but I think we might as well not rely
on that assumption.

super() uses 0 as mid for its callinfo, so we need to check for that to
avoid a segfault when using dump_all.

This commit dumps the `mid` of the imemo callinfo when calling
`ObjectSpace.dump_all`.