GH-438: Rename components to be clearer for their intention

[ascopes]

Tidy up prior to the crux of GH-438's implementation to avoid confusion and ambiguity.

• Rename components relating to proto files to be clear they are operating on source files.
• Rename the SourceCodeGenerator "monolith" to ProtobufBuildOrchestrator, which more accurately describes what this component really does.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 87.68%. Comparing base (1ef2c21) to head (3799d79). Report is 5 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #449 +/- ## ========================================== + Coverage 87.61% 87.68% +0.08% ========================================== Files 32 32 Lines 1113 1112 -1 Branches 76 76 ========================================== Hits 975 975 + Misses 104 103 -1 Partials 34 34 ``` | [Files with missing lines](https://app.codecov.io/gh/ascopes/protobuf-maven-plugin/pull/449?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Ashley) | Coverage Δ | | |---|---|---| | [...enplugin/generation/ProtobufBuildOrchestrator.java](https://app.codecov.io/gh/ascopes/protobuf-maven-plugin/pull/449?src=pr&el=tree&filepath=protobuf-maven-plugin%2Fsrc%2Fmain%2Fjava%2Fio%2Fgithub%2Fascopes%2Fprotobufmavenplugin%2Fgeneration%2FProtobufBuildOrchestrator.java&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Ashley#diff-cHJvdG9idWYtbWF2ZW4tcGx1Z2luL3NyYy9tYWluL2phdmEvaW8vZ2l0aHViL2FzY29wZXMvcHJvdG9idWZtYXZlbnBsdWdpbi9nZW5lcmF0aW9uL1Byb3RvYnVmQnVpbGRPcmNoZXN0cmF0b3IuamF2YQ==) | `85.25% <100.00%> (ø)` | | | [...bufmavenplugin/generation/SourceRootRegistrar.java](https://app.codecov.io/gh/ascopes/protobuf-maven-plugin/pull/449?src=pr&el=tree&filepath=protobuf-maven-plugin%2Fsrc%2Fmain%2Fjava%2Fio%2Fgithub%2Fascopes%2Fprotobufmavenplugin%2Fgeneration%2FSourceRootRegistrar.java&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Ashley#diff-cHJvdG9idWYtbWF2ZW4tcGx1Z2luL3NyYy9tYWluL2phdmEvaW8vZ2l0aHViL2FzY29wZXMvcHJvdG9idWZtYXZlbnBsdWdpbi9nZW5lcmF0aW9uL1NvdXJjZVJvb3RSZWdpc3RyYXIuamF2YQ==) | `100.00% <ø> (ø)` | | | [...protobufmavenplugin/mojo/AbstractGenerateMojo.java](https://app.codecov.io/gh/ascopes/protobuf-maven-plugin/pull/449?src=pr&el=tree&filepath=protobuf-maven-plugin%2Fsrc%2Fmain%2Fjava%2Fio%2Fgithub%2Fascopes%2Fprotobufmavenplugin%2Fmojo%2FAbstractGenerateMojo.java&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Ashley#diff-cHJvdG9idWYtbWF2ZW4tcGx1Z2luL3NyYy9tYWluL2phdmEvaW8vZ2l0aHViL2FzY29wZXMvcHJvdG9idWZtYXZlbnBsdWdpbi9tb2pvL0Fic3RyYWN0R2VuZXJhdGVNb2pvLmphdmE=) | `100.00% <ø> (ø)` | | | [.../protobufmavenplugin/sources/SourceGlobFilter.java](https://app.codecov.io/gh/ascopes/protobuf-maven-plugin/pull/449?src=pr&el=tree&filepath=protobuf-maven-plugin%2Fsrc%2Fmain%2Fjava%2Fio%2Fgithub%2Fascopes%2Fprotobufmavenplugin%2Fsources%2FSourceGlobFilter.java&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Ashley#diff-cHJvdG9idWYtbWF2ZW4tcGx1Z2luL3NyYy9tYWluL2phdmEvaW8vZ2l0aHViL2FzY29wZXMvcHJvdG9idWZtYXZlbnBsdWdpbi9zb3VyY2VzL1NvdXJjZUdsb2JGaWx0ZXIuamF2YQ==) | `100.00% <100.00%> (ø)` | | | [...es/protobufmavenplugin/sources/SourceResolver.java](https://app.codecov.io/gh/ascopes/protobuf-maven-plugin/pull/449?src=pr&el=tree&filepath=protobuf-maven-plugin%2Fsrc%2Fmain%2Fjava%2Fio%2Fgithub%2Fascopes%2Fprotobufmavenplugin%2Fsources%2FSourceResolver.java&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Ashley#diff-cHJvdG9idWYtbWF2ZW4tcGx1Z2luL3NyYy9tYWluL2phdmEvaW8vZ2l0aHViL2FzY29wZXMvcHJvdG9idWZtYXZlbnBsdWdpbi9zb3VyY2VzL1NvdXJjZVJlc29sdmVyLmphdmE=) | `83.06% <100.00%> (ø)` | |