feat(props): Add support to overwrite properties based on a UP_CLUSTE…

[bjagg]

…R env property

Resolves #1747

Checklist

• the individual contributor license agreement is signed
• commit message follows commit guidelines
• tests are included
• documentation is changed or added

Description of change

Client wished to place all properties in a single set of properties files that would work in test, and prod. To support this, a system environment variable UP_CLUSTER can be set. If properties are found that start with that value plus ., then those key/value pairs will be added back, overwriting existing values, without the prefix.

For example if UP_CLUSTER=prod is set in the System environment, an initial properties set of:

url=www.github.com
dev.url=github.com
prod.url=www.mycompany.com

will then become the following, post-processed:

url=www.mycompany.com
dev.url=github.com
prod.url=www.mycompany.com

Also, -Dcluster=prod added to CATALINA_OPTS, JAVA_OPTS, etc. will also work.

N.B. UP_CLUSTER takes precedent over the -Dcluster JVM argument.

[ChristianMurphy]

Do we want to do this per property?
Or would it be better to generalize this to have different properties files for different envs, so multiple properties can be customized?

[bjagg]

Do we want to do this per property?
Or would it be better to generalize this to have different properties files for different envs, so multiple properties can be customized?

Before this PR, different properties files was the only option. Thus, Ops folks would have a separate uPortal.properties, global.properties, notifications.properties, etc. for each environment. This is still a good practice.

This PR is a convenience enhancement that will allow all those versions of a same file to be brought back into a single file while still supporting multiple environments.