Cleanup SpacetimeDB name usages

[jdetter]

Description of Changes

Please describe your change, mention any related tickets, and so on here.

• Fixed any instances where SpacetimeDB is not spelled correctly

API and ABI breaking changes

If this is an API or ABI breaking change, please apply the
corresponding GitHub label.

• This may have some small API breakages in tests and things, and we changed the name of a file on disk although I'm not sure that actually impacts the API at all. This probably breaks the API somehow but not in a meaningful way.

Expected complexity level and risk

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where 1 is a trivial change, and 5 is a deep-reaching and complex change.

This complexity rating applies not only to the complexity apparent in the diff,
but also to its interactions with existing and future code.

If you answered more than a 2, explain what is complex about the PR,
and what other components it interacts with in potentially concerning ways.

0

[mamcx]

LGTM. I check the syntax coloring running the repl and looks fine.