Clarified error message for non-writable options table.

[sergeymitr]

Changes proposed in this Pull Request:

When the wp_options table is not writeable, connecting Jetpack will result in the error Verification secrets not found.
This PR clarifies the error, informing the user that they need to confirm the options table is writable.

Does this pull request change what data or activity we track or use?

No.

Testing instructions:

1. Disconnect Jetpack (if connected).
2. Remove AUTO_INCREMENT from the wp_options table:

ALTER TABLE wp_options CHANGE option_id option_id bigint(20) unsigned NOT NULL;

3. Try to connect Jetpack.
4. The "Set up Jetpack" page should be reloaded, the error message "Could not save secrets. Please confirm that the options table is writable." should show up.

Before:

After:

Proposed changelog entry for your changes:

• Displaying a clarified error message when the options table is not writable.

[test-case-reminder]

Here are some suggested test cases for this PR.

Connection

• In-place connection with free plan
• In-place connection with paid plan
• In-place connection with product purchase
• Classic connection. Use Safari, or set a constant JETPACK_SHOULD_NOT_USE_CONNECTION_IFRAME to true
• Disconnect/reconnect connection
• Secondary user connection
• Connection on multisite

Verify that the changes are compatible with the plugins that use the connection package.

• WooCommerce Payments
• Jetpack Boost
• Previous versions of Jetpack

If you think that suggestions should be improved please edit the configuration file here. You can also modify/add test-suites to be used in the configuration file.

[jetpackbot]

Scheduled Jetpack release: December 1, 2020.
Scheduled code freeze: November 23, 2020

E2E results is available here (for debugging purposes): https://jetpack-e2e-dashboard.herokuapp.com/pr-17767

Thank you for the great PR description!

When this PR is ready for review, please apply the [Status] Needs Review label. If you are an a11n, please have someone from your team review the code if possible. The Jetpack team will also review this PR and merge it to be included in the next Jetpack release.

Generated by 🚫 dangerJS against 88fa36c

[anomiex]

Looks straightforward, and the only change since Jeremy's review was a wording adjustment he suggested.