feat: rearrange core contracts addresses

[nmlinaric]

Description

Moved Router and Executor contract addresses to bridge and introduced new adminChangeRouterAndExecutor function for changing the corresponding addresses.
This way all handlers will always look at the same Router and Executor contracts and if required we can easily point them to new contracts if required (this reduces the number of contracts that need to be redeployed).

Related Issue Or Context

Closes: #16

How Has This Been Tested? Testing details.

• unit tests
• e2e tests

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• [x} 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 Sygma-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

[nmlinaric]

This should be merged after #43 & #44