[MNG-8655] Provide a SPI to parse settings using a different language

**[Guillaume Nodet](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=gnt)** opened **[MNG-8655](https://issues.apache.org/jira/browse/MNG-8655?redirect=false)** and commented

Rewriting the whole SettingsBuilder may be a bit too much, so maybe a `SettingsParser` SPI similar to `ModelParser` would be handy to support extensions.

See https://github.com/microbean/microbean-maven-cdi/blob/master/src/main/java/org/microbean/maven/cdi/YamlSettingsBuilder.java

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**Affects:** 4.1.0

**Issue Links:**
- [MNG-6435](https://issues.apache.org/jira/browse/MNG-6435) DefaultSettingsBuilder assumes all SettingsReader/Writer impls will use XML

Start by comparing the existing SettingsBuilder approach with the ModelParser SPI, using the linked YamlSettingsBuilder as a reference for extension needs. Determine how a SettingsParser SPI should support non-XML settings and address the SettingsReader/Writer assumption described in MNG-6435. Done means the extension point is defined and alternate-language settings parsing can be supported.

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