Support partially filled composite IDs

[sickfar]

Description

Summary of the change:
This PR supports a new scenario of Composite ID usage.
In case when composite ID can be partially generated (autoGenerated UUID or database-side autoIncrement column), I should be able to specify only static required CompositeID parts.

Detailed description:

• What: CompositeID is now longer required to be fully constructed if part of it based on generated columns
• Why: If I have a multi-tenant application, and the multi-tenancy is provided by a specific DB column, I want to be able to specify this tenant ID and leave the the in-tenant ID to be generated by database. In my own case, I have a project with "School" as tenant and school_id column as constant component of composite primary key, and "Client" with client_id generated from a sequence, which I do not really need to specify when creating a new entity.

object ClientTable : CompositeIdTable("clients") {
    val schoolId = long("school_id").entityId()
    val clientId = long("id").autoIncrement().entityId()
    override val primaryKey = PrimaryKey(schoolId, clientId)
}

// before this PR:
Client.new(CompositeID {
    it[ClientTable.schoolId] = schoolId
    it[ClientTable.clientId] = getNextClientId() // fetch from some sequence even though clientId is defined as autoIncrement(). NPE thrown if not provided
}) { /* init */ }

// after this PR clientId defined as autoIncrement() will be generated by database as it designed
Client.new(CompositeID {
    it[ClientTable.schoolId] = schoolId
}) { /* init */ }

• How: writeValues in EntityClass will be written only if column is presented in CompositeID. To avoid mistakes by forgotten column, missed column is additionally checked to be AutoIncrementColumn or to have defaultValueFun. To be completely reloaded by entityCache, id will be set to null after setting writeValues

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Type of Change

Please mark the relevant options with an "X":

• Bug fix
• New feature
• Documentation update

Updates/remove existing public API methods:

• Is breaking change

Affected databases:

• MariaDB
• Mysql5
• Mysql8
• Oracle
• Postgres
• SqlServer
• H2
• SQLite

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

[bog-walk]

Thanks very much for this well-needed addition and for opening a PR @sickfar
Also thanks for preemptively rebasing and updating the docs and tests 👍

If you come across any other oversights when using composite keys (etc.), please feel free to contribute again, either by opening an issue on YouTrack or with another PR.