Create a test calling a reducer with large args

[kim]

As a regression test for #1646

[kim]

Any of the assignees who knows about the max buffer size is welcome to implement :)

[cloutiertyler]

Moving to 1.0 because we're being ruthless about 0.12.

[gefjon]

How large is "large?"

[bfops]

It sounds like we don't know exactly https://github.com/clockworklabs/SpacetimeDB/pull/1646#discussion_r1735063975