feat!: EXPOSED-555 Allow read-only suspendable transactions

[RenanKummer]

Description

Summary of the change: Regular transaction management allow callers to configure if new transactions should be read-only. This change adds the same behavior to suspendable transactions.

Detailed description:

• What: A readOnly parameter has been added for newSuspendTransaction.
• Why: Regular transactions allow readOnly to be configured by callers. As per JetBrains Exposed documentation, this behavior is supposed to be the same for regular and suspendable transactions, but the parameter was missing for suspendable transactions.
• How: The parameter was added as optional (nullable with the default value set to null) to avoid breaking changes as much as possible. It is passed ahead to internal functions in order to create the transaction either as read-only based on caller's configuration or as the original behavior for existing code.

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Type of Change

Please mark the relevant options with an "X":

• New feature

Updates/remove existing public API methods:

• Is breaking change

Affected databases:

• Mysql5
• Mysql8
• Postgres

Checklist

• Unit tests are in place
• The build is green (including the Detekt check)
• All public methods affected by my PR has up to date API docs
• Documentation for my change is up to date

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Related Issues

https://youtrack.jetbrains.com/issue/EXPOSED-555/newSuspendedTransaction-support-for-readOnly