AMPS-1394 Explicitly set server.ssl.key-password for Bitbucket 5.0+

Failure to explicitly set server.ssl.key-password for Bitbucket Server 5.0+ means the default password (changeit) is used. The way AMPS works with Bitbucket Server 4.x is that the "key store password" is used as the "key password" too (actually Tomcat provides this behaviour, because in BBS 4.x AMPS just generates a server.xml). This just implements that same behaviour when AMPS is starting Bitbucket Server 5.0+

Note, that in Tomcat or Spring Boot it is possible to set a different password for the key itself versus the keystore. However AMPS only supports a single password, provided via the httpsKeystorePass provided to the maven-amps-plugin.

For background see:

• https://ecosystem.atlassian.net/browse/AMPS-1394

• https://jira.atlassian.com/browse/BSERVDEV-15376

Build: https://ecosystem-bamboo.internal.atlassian.com/browse/AMPS-AMPSB6D3X3-2