Add analyze imports libs (SPICE-0001) (#695)

This adds a new feature to build a dependency graph of Pkl programs, following the SPICE outlined in https://github.com/apple/pkl-evolution/pull/2.

It adds:
* CLI command `pkl analyze imports`
* Java API `org.pkl.core.Analyzer`
* Pkl stdlib module `pkl:analyze`
* pkl-gradle extension `analyze`

In addition, it also changes the Gradle plugin such that `transitiveModules` is by default computed from the import graph.

pkl-core/src/test/files/LanguageSnippetTests/input-helper/analyze/a.pkl

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+import "b.pkl"

pkl-core/src/test/files/LanguageSnippetTests/input-helper/analyze/cyclicalA.pkl

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+import "cyclicalB.pkl"

pkl-core/src/test/files/LanguageSnippetTests/input-helper/analyze/cyclicalB.pkl

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+import "cyclicalA.pkl"

pkl-core/src/test/files/LanguageSnippetTests/input-helper/analyze/globImport.pkl

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+import* "[ab].pkl"