Override QA::Page::Base#inspect for prettier msgs

What does this MR do?

Overrides inspect in the base page object class to improve failure messages. For example:

expected QA::Page::File::Show not to have file "QA Test - File name"

Instead of:

expected #<QA::Page::File::Show:0x000055c6511e07b8 @retry_later_backoff=60> not to have file "QA Test - File name"

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• [-] Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content