Feature/cms 660 show read-only settings when allowAdminChanges is disabled

[i-just]

Description

Shows read-only settings when allowAdminChanges is disabled.

• switched .revision-notice to a generic .content-notice class so that the styles can be reused for other purposes too
• when admin changes are disallowed, the “Settings” main nav item and all the subpages (except for the plugin settings) are shown, with all the fields and forms being disabled and with a notice at the top of every page
• plugins can opt into having their settings shown when allowAdminChanges is disabled; to do so, they need to ensure none of the settings are editable in such case and implement public function canViewReadOnlySettings(): bool; to return true
• src/events/RegisterCpSettingsEvent has a new public property $readOnlyModeReady, which is set to false by default; if the settings changes manipulated via the event are ready to be displayed in a non-editable way, set it to true to have them show when admin changes are not allowed.

Related issues

cms-660

[linear]

CMS-660 Show read-only settings when allowAdminChanges == false

[Mosnar]

Love this! It might be worth adding a "Learn More" button to a KB article explaining why settings can't/shouldn't be changed in production. Newer Craft developers or over-confident clients might read the current disclaimer as instructions to simply turn on "allowAdminChanges" and potentially get themselves in a mess.

[gcamacho079]

@i-just awesome! I pinged you on the Notion page for this feature as I had some follow-up questions.

[i-just]

thanks @gcamacho079! I actioned all your comments. Extra info on the Notion page. LMK if anything doesn't make sense.

[gcamacho079]

Thanks for knocking out those changes, @i-just! A couple more things I noticed that should also get the disabled attribute:

• The .menubtn for “Selectable {{ element }} condition” on Entries and Assets field settings pages
• The “Static Rows” field (and the conditionally-revealed fields) on Table field settings
• Info toggle buttons inside disabled table fields (for example, in the “Site Settings” table heading on the Matrix field settings page)