feat(client): add permanent flag to CLI and publisher

[mlegner]

Description

Currently, blobs are "permanent" as default and can be stored as "deletable" through the --deletable CLI option and a deletable query parameter on the publisher. We want to change this default behavior in the future, at which point we need a way to specify a blob as "permanent". Adding the --permanent flag in the same release where the default is changed is a bit dangerous as all users would have to change their invocations at exactly that point.

Adding the --permanent flag now allows users to already start calling walrus store --permanent [...] to make sure the behavior is unaffected by the later default change. Additionally, we log a warning about the upcoming default change from permanent to deletable if neither flag is specified.

The plan would then be to keep the --deletable around for some time longer and log a different warning about the default change if neither flag is specified.

Contributes to WAL-911.

Test plan

Manual checks.

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Release notes

• Publisher: Add a permanent query parameter. Warning: In the future, blobs will be stored as deletable by default; to keep the current behavior, you need to add the permanent=true query parameter.
• CLI: Add a --permanent option to the store and store-quilt commands. Warning: In the future, blobs will be stored as deletable by default; to keep the current behavior, you need to add the --permanent option when storing blobs.

[github-actions]

Warning: This PR modifies one of the OpenAPI files. Please consider the
following:

• Make sure the API changes are backwards compatible.
• Make sure to follow existing conventions for any added parameters, requests, and
  responses.
• Make sure the generated HTML files do not contain errors.
• This probably requires release notes and maybe changes to the documentation.

cc @jpcsmith @mlegner

[github-actions]

Warning: This PR modifies the Walrus CLI. Please consider the following:

• Make sure the changes are backwards compatible. Consider deprecating options before
  removing them.
• Generally only use long CLI options, not short ones to avoid conflicts in the
  future.
• If you added new options or features, or modified the behavior, please document the
  changes in the release notes of the PR and update the documentation in the docs/book
  directory.

[liquid-helium]

Thanks @mlegner for adding this new behavior, looks good to me, I left only one comment.

[liquid-helium]

💯