Fix number of native tokens in migration summary

[cpl121]

Bug description

The sum of the native tokens is not correct, we need to count the different types of native tokens, not the number of bags of native tokens. In the example above, there are 2 types of native tokens, BOX_COIN and TOOL_COIN, but the number of native tokens is 6

iota/apps/wallet-dashboard/lib/utils/migration/groupStardustObjectsByMigrationStatus.ts

Line 79 in 78f337f

totalNativeTokens += parseInt(outputObjectFields.native_tokens.fields.size);