Show better error when installed gemspecs are unreadable

[deivid-rodriguez]

What was the end-user or developer problem that led to this PR?

Bug report template is printed when an installed gemspec is unreadable.

What is your fix for the problem, implemented in this PR?

Make sure we raise an error class that results in a nice error being printed instead of the error report template. Now the error is like this:

$ bundle install
Fetching gem metadata from https://rubygems.org/.
There was an error while trying to read from `/path/to/ruby/3.3.0/lib/ruby/gems/3.3.0/specifications/debug-1.9.1.gemspec`. It is likely that you need to grant read permissions for that path.

Fixes #7586.

Make sure the following tasks are checked

• Describe the problem / feature
• Write tests for features and bug fixes
• Write code to solve the problem
• Make sure you follow the current code style and write meaningful commit messages without tags

[segiddins]

Could we instead wrap the access in a filesystem_access block?

[deivid-rodriguez]

Good idea, just made that change!