Fix installation and update SQL scripts

[richard67]

Pull Request for [SOC 21] Add a Scheduled Tasks Infrastructure to Joomla .

Summary of Changes

This PR fixes following:

• Wong value 1 instead of '' was used for the folder column when inserting com_scheduler into the extensions table in base.sql.
• Alpha order the plugins inserts into the extensions table in files base.sql and 4.1.0-2021-11-20.sql.
• Adjust data type of the the #__scheduler_tasks table's asset_id column to how we have it elsewhere, e.g. remove the UNIQUE constraint in the SQL scripts for MySQL in files extensions.sql and 4.1.0-2021-11-20.sql.
• Use numeric default values for numeric columns of the the #__scheduler_tasks table in files extensions.sql and 4.1.0-2021-11-20.sql.
• Add missing inserts into extensions table for other plugins to file 4.1.0-2021-11-20.sql.
• Add missing inserts into action logs tables to file 4.1.0-2021-11-20.sql.
• Move insert of mail templates to the end in file 4.1.0-2021-11-20.sql because these belong to the previously inserted extensions.
• Diverse code style adjustments (we don't really have an SQL code style but we should do things like they are done elswhere).

[ditsuke]

We are also missing plg_task_checkfiles in both the install and update scripts.

[richard67]

How shall I know. Well, merge my PR and then you can add that. I am at work so can’t do anything else before tonight my time.

[ditsuke]

Thanks!