Relayer and Validator node types are represented as enum flags in E2E framework

[jelacamarko]

Description

In e2e test framework, InitTestServer method now has a flags field instead of isValidator, relayer fields.
flags field represents enum flags.
If we want to init server as validator and relayer, we can pass Validator | Relayer as value for flags.
HasFlag function is used to check if the flag is present in flags.

Changes include

• Bugfix (non-breaking change that solves an issue)
• Hotfix (change that solves an urgent issue, and requires immediate attention)
• New feature (non-breaking change that adds functionality)
• Breaking change (change that is not backwards-compatible and/or changes current functionality)

Breaking changes

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Checklist

• I have assigned this PR to myself
• I have added at least 1 reviewer
• I have added the relevant labels
• I have updated the official documentation
• I have added sufficient documentation in code

Testing

• I have tested this code with the official test suite
• I have tested this code manually

Manual tests

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Documentation update

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Additional comments

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[Stefan-Ethernal]

Nice. I've put a couple of minor suggestions.