Update refreshKey event

[nmlinaric]

Description

Update refreshKey event that is emits hash string which will be used to prevent changes in between voting for refresh and refresh occurring.

Related Issue Or Context

Closes: #595

How Has This Been Tested? Testing details.

Unit tests

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation

Checklist:

• I have commented my code, particularly in hard-to-understand areas.
• I have ensured that all acceptance criteria (or expected behavior) from issue are met
• I have updated the documentation locally and in chainbridge-docs.
• I have added tests to cover my changes.
• I have ensured that all the checks are passing and green, I've signed the CLA bot

[lastperson]

If the topology hash is always expected to use the same function, then it would be more optimal to use bytesXX type instead of a string.

[nmlinaric]

If the topology hash is always expected to use the same function, then it would be more optimal to use bytesXX type instead of a string.

Had a discussion about that with the guys working on backend side, the hash could be larger than 32 bytes, maybe in the future comes a way we can optimize it.