Make sure, that get_coin_for_transaction returns a coin object with enough balance

[wulfraem]

Description

When the function get_coin_for_transaction retrieves a Coin object, we have to make sure, that this coin has a balance big enough, that we can actually use it.

Motivation

Getting a Coin object with low balance might lead to our transaction failing. Even worse, if we get the same Coint object for every get_coin_for_transaction call, this would lock out the current user from making writing operations to the chain. Also the current implementation is not paging through results, which should be changed.

To-do list

Add more if points are missing

• use paging when fetching coins
• add checks for a minimum balance (value TBD)
• add tests

Change checklist

Add an x to the boxes that are relevant to your changes, and delete any items that are not.

• The feature or fix is implemented in Rust and across all bindings whereas possible.
• The feature or fix has sufficient testing coverage
• All tests and examples build and run locally as expected
• Every piece of code has been document according to the documentation guidelines.
• If conceptual documentation (mdbook) and examples highlighting the feature exist, they are properly updated.
• If the feature is not currently documented, a documentation task Issue has been opened to address this.