Make tool callbacks optional across SDKs #272

Job	Run time
Rust SDK Tests (macos-latest)	5m 59s
Rust SDK Bundled CLI Build (macos-latest)	3m 41s
Rust SDK Tests (windows-latest)	11m 29s
Rust SDK Bundled CLI Build (windows-latest)	3m 39s
Rust SDK Tests (ubuntu-latest)	5m 57s
Rust SDK Bundled CLI Build (ubuntu-latest)	3m 12s
	33m 57s

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