[INDEXER_CLIENT] get_substate without version specified returns earliest substate

[humb1t]

Describe the bug

Maybe it's expected behavior, but get_substate method when no exact version specified returns not the latest, but earliest version.

To Reproduce

1. Upload template
2. Create component
3. Make actions to change it's state
4. Call the following code:

            client_clone
                .get_substate(GetSubstateRequest {
                    address: substate_id,
                    version: None,
                    local_search_only: false,
                })
                .await
                .map(|response| response.substate)

Expected behavior

Would be nice to get the latest substate version when you are defining version: None or have an ability to configure which version to return. For example instead of Option<VersionN> use enum with variants: Latest, First, N(u64).

Screenshots
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Desktop (please complete the following information):

• OS & Version: [e.g. iOS 10.2.1]
• Browser & Version [e.g. chrome v71.0.12345]

Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Browser & Version [e.g. stock browser v0.1.2]

Additional context
Add any other context about the problem here.

[ksrichard]

PR: #1261