[#275] Show region selector feedback when benchmark not found

[wayangalihpratama]

• The benchmark selection does not save when you go to next pages and then back #275

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"Issue:
When selecting the Non-metropolitan Urban region, the benchmark for that region and year is not found ({ "detail": "Benchmark not found" }).
Therefore, we need to add a toast or notification to inform the user that the benchmark is not found."

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