Contract Explorer: Contract storage filters

[quietbits]

1. The filter logic is "or", meaning that selecting more filters includes more records. We could implement "and" logic (narrowing down selection), making the filters dynamic. Adding more data to store locally might slow the UI, though.
2. We need an "Apply" button to apply the selected filters. Because we can have thousands of records, we can't make updates on the fly as the filters are selected. For now, I added a basic button, so we have "Apply" and "Clear filter" buttons.
3. What should be the logic for selecting value filters? I'm using object keys from decoded value XDR, and we might end up with numbers. For example, CAS3FL6TLZKDGGSISDBWGGPXT3NRR4DYTZD7YOD3HMYO6LTJUVGRVEAM (Mainnet). key filters are much more predictable than value, which can be pretty much anything.
4. How should we handle very long lists of filters? For example, CDVQVKOY2YSXS2IC7KN6MNASSHPAO7UN2UR2ON4OI2SKMFJNVAMDX6DP (Mainnet) has a very long list of value filters.
5. We need to keep checking how we handle thousands of records. On my machine, CDVQVKOY2YSXS2IC7KN6MNASSHPAO7UN2UR2ON4OI2SKMFJNVAMDX6DP (Mainnet) with 6k+ records at this time, seems OK. It takes a few seconds on the initial load, and then the loader is displayed when sorting. But the UI doesn't feel sluggish; it just takes longer to load the result.
6. Should we display the filtered results count?
7. I will add tests in a follow-up PR once we're all set with the UI.

[stellar-jenkins]

Preview is available here:
http://laboratory-pr1233.previews.kube001.services.stellar-ops.com/

[quietbits]

We need to decode key and value XDR to get filter values.

[stellar-jenkins]

Preview is available here:
http://laboratory-pr1233.previews.kube001.services.stellar-ops.com/

[stellar-jenkins]

Preview is available here:
http://laboratory-pr1233.previews.kube001.services.stellar-ops.com/

[janewang]

Should we display the filtered results count?
No, I think there is no need. Once they filter down the list, maybe the user can download

[jeesunikim]

I'm getting a warning for missing key prop in console.