Add multiple component support

[lucian-ioan]

Closes #63

[elasticmachine]

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• Start Time: 2022-10-28T09:30:29.995+0000

• Duration: 3 min 42 sec

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[endorama]

Overall the proposed solution is ok. Please fix tests and make sure this work in the case of a single component or zero components.

[lucian-ioan]

Currently, components that are either not found in the config or left empty in the fragments are considered unidentified.

This is reflected in the changelog with the title and as an unidentified component field.

With additonal logic, unidentified can be split into unmatched and unspecified for components not found in the config or left empty in the fragments.

What do you think @endorama?

[endorama]

I think this should be addressed with a fatal error: if a component is not matched or identified the tool should produce an error and stop processing the consolidated changelog.

We can notify users of unmatched and unspecified components in the changelog linter, at this stage we want to output correct release notes that can be reused.

[endorama]

Discussing how the errors should be handled we noticed there are multiple cases for components configuration based on config and fragment value. Here is the authoritative description of how the tool will manage them (will be updated during the life of this PR).

components configuration value	Fragment component field value	Release notes generated	Effect
[]	empty	✔	Not using components here, release notes should not use components.
["single"]	empty	✔	We assume all fragments are using the configured component.
["single"]	"foobar"	❌	Component known and with incorrect value, emit error and stop processing.
["first", "second"]	empty	❌	Component unknown and cannot be assumed, emit error and stop processing.
["first", "second"]	"foobar"	❌	Component known and with incorrect value, emit error and stop processing.
["first", "second"]	"first"	✔	Component known and with correct value.