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Thread-safe property resolution for concurrent execution of the same job: Added JobBuilder.createJob(String, Consumer<PropertyResolver>>) and deprecated JobProperties

Thanks to https://github.com/jblayneyXpanxion for these changes:

• Updated config to use explicit component scans, and a config package for bean definitions to allow for more creative integration test setups with mock beans.
• Added the ability to schedule jobs with parameters specified via JobConfig.
• Added the ability to schedule jobs via name that are defined in a job bean that is constructed on-demand. This is helpful when job steps are defined as beans with parameters resolved via spel notation based off JobParameters/JobContext that is only available in the StepScope at job construction.
• Updated the default group to be Quartz's default group (specified as a null param to JobKey), rather than a hard-coded "group" string.
• Bumped Spring Boot to 2.2.7.RELEASE

Convenience methods + timezone + docs update

Decoupled Quartz and core APIs, thus preventing transitive Quartz dependencies unless needed.

Ensuring Java 8 compatibility by building with source and target levels of 1.8