Execute in all databases defined in bee.properties

[danielfariati]

It would be cool if we could execute bee in all defined databases at once. Especially if we think about schema/database multi-tenancy. The commands that I'd use are:
dbchange:up
dbchange:down
data:validate
schema:validate

The ideal is to run simultaneously, for better performance (maybe even offering the option to configure the number of threads). Something like:
bee dbchange:up -a, to run in every database
bee dbchange:up -a 5 to run in every database, with 5 parallel threads

If there were errors, the log would be divided by database.
Example:
DATABASE_1
WARNING: Failed to execute: alter TABLE table change id id int (11);

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DATABASE_2
WARNING: Failed to execute: alter TABLE table change id id int (11);