CNS-268: Implement Plans module

[oren-lava]

• Please check if the PR fulfills these requirements

• [ V ] Commit message follows the Contribution Guidelines
• [ V ] Tests ran locally and added/modified if needed
• [ X ] Docs have been added/updated, if applicable
• [ V ] If applicable - JIRA ticket ID was added

• What kind of change does this PR introduce? (Bug fix, feature, unit tests, docs update, ...)
  Feature (new module)

• What is the current behavior? (You can also link to an open issue here)
  None

• What is the new behavior (if this is a feature change)?
  The packages module's goal is to manage subscriptions packages in a similar way to the spec module. To create a buyable package, it must be proposed and voted in the network. Packages can be updated. Old versions of packages are removed after a given time (each package has a duration field for that). Additionally, I've implemented two queries for this module: show-all-packages and show-package-info, like the spec module.

The entryFixation library's goal is to create a standard set of APIs to manage fixated entities. The packages module uses the new entryFixation library.

• Please describe what manual tests you ran, if applicable
  I've created a number of unit tests for the module, which all passed. I've checked that the module works correctly with a local node.

• Other information:
  In the PR original submission, I didn't merge main yet to ease the code check. So the e2e tests might fail.

[oren-lava]

List of files that I've created/modified to review (meaning: without scaffolded files):

Packages module:
app/app.go
app/keepers/lavaKeepers.go
proto/packages/package.proto
proto/packages/package_unique_index.proto
proto/packages/package_versions_storage.proto
proto/packages/packages_add_proposal.proto
proto/packages/query.proto
testutil/keeper/keepers_init.go
testutil/keeper/packages.go
x/packages/client/cli/tx.go
x/packages/client/proposal_handler.go
x/packages/client/rest/rest.go
x/packages/client/utils/utils.go
x/packages/keeper/epoch_start.go
x/packages/keeper/grpc_query_show_all_packages.go
x/packages/keeper/grpc_query_show_package_info.go
x/packages/keeper/keeper.go
x/packages/proposal_handler.go
x/packages/types/addproposal.go
x/packages/types/errors.go
x/packages/types/expected_keepers.go
x/packages/types/proposal.go
x/packages/types/types.go

Entry Fixation library:
common/entryFixation.go
proto/common/entryFixation.proto

Other:
cookbook/package_json_example.json