internal: move all struct* packages into libs/structs/

[denik]

Changes

Pure move, no other changes.

Why

Better logical grouping. The structtag and structpath are brought one level higher as they are not just relevant for structdiff but for all struct* packages.

[eng-dev-ecosystem-bot]

Run: 17728583849

	Env	✅​pass	🔄​flaky	🙈​skip
🔄​	aws linux	310	2	526
✅​	aws windows	313		525
🔄​	aws-ucws linux	415	9	424
🔄​	aws-ucws windows	416	9	423
✅​	azure linux	312		525
🔄​	azure windows	310	3	524
✅​	azure-ucws linux	424		423
✅​	azure-ucws windows	425		422
✅​	gcp linux	311		527
✅​	gcp windows	312		526

13 failing tests:

Test Name	aws linux	aws-ucws linux	aws-ucws windows	azure windows
TestAccept	🔄​flaky	✅​pass	✅​pass	🔄​flaky
TestAccept/bundle/deploy/alerts/basic	🔄​flaky	✅​pass	✅​pass	✅​pass
TestAccept/bundle/deploy/dashboard/detect-change	✅​pass	🔄​flaky	🔄​flaky	✅​pass
TestAccept/bundle/deploy/dashboard/generate_inplace	✅​pass	🔄​flaky	🔄​flaky	✅​pass
TestAccept/bundle/deploy/dashboard/nested-folders	✅​pass	🔄​flaky	🔄​flaky	✅​pass
TestAccept/bundle/deploy/dashboard/simple	✅​pass	🔄​flaky	🔄​flaky	✅​pass
TestAccept/bundle/deploy/dashboard/simple_outside_bundle_root	✅​pass	🔄​flaky	🔄​flaky	✅​pass
TestAccept/bundle/deploy/dashboard/simple_syncroot	✅​pass	🔄​flaky	🔄​flaky	✅​pass
TestAccept/bundle/deployment/bind/dashboard	✅​pass	🔄​flaky	🔄​flaky	✅​pass
TestAccept/bundle/deployment/bind/dashboard/recreation	✅​pass	🔄​flaky	🔄​flaky	✅​pass
TestAccept/bundle/templates/default-python/integration_classic	✅​pass	✅​pass	✅​pass	🔄​flaky
TestAccept/bundle/templates/default-python/integration_classic/DATABRICKS_CLI_DEPLOYMENT=direct-exp/UV_PYTHON=3.12	✅​pass	✅​pass	✅​pass	🔄​flaky
TestDashboardAssumptions_WorkspaceImport	✅​pass	🔄​flaky	🔄​flaky	✅​pass