feat: update tx list with observeTransactions

[HashEngineering]

Issue being fixed or feature implemented

Related PR's and Dependencies

Screenshots / Videos

How Has This Been Tested?

• QA (Mobile Team)

Checklist:

• I have performed a self-review of my own code and added comments where necessary
• I have added or updated relevant unit/integration/functional/e2e tests

[Syn-McJ]

Looks good so far, updating rows is working in my testing.

One potential optimization could be made: if we move grouping by date into the ViewModel from the fragment:

val groupedByDate = transactionViews.groupBy {
     Instant.ofEpochMilli(it.time).atZone(ZoneId.systemDefault()).toLocalDate()
}

then we might be able keep a grouped map of transactions, something like this:

private val _transactions = MutableLiveData<Map<LocalDate, List<TransactionRowView>>>()

Then, finding the proper row to change is easier since you only need to get the group based on the transaction date and search within it.

This probably isn't necessary if there is already enough performance benefits achieved.