Fix Source Code Extraction to Stack Traces (regression via rails)

[chodges15]

Describe the idea
Currently, the Ruby Sentry SDK provides stack traces that include the file name, line number, and method name where an error occurred. However, it does not include the actual lines of source code. This feature is crucial for debugging, especially when dealing with third-party code, as it provides immediate context around the error without requiring developers to manually locate and open the files.

The feature request is to add functionality to the Ruby Sentry SDK to extract and include source code snippets in stack traces. This can be achieved by implementing a mechanism similar to the CodeExtractor class in the Bugsnag SDK, which reads the relevant files and attaches the surrounding lines of code to the stack trace.

Why do you think it's beneficial to most of the users

1. Improved Debugging: Including source code snippets in stack traces allows developers to quickly understand the context of an error, making it easier to diagnose and fix issues.

2. Third-Party Code: When errors occur in third-party libraries, developers may not be familiar with the code. Providing the surrounding lines of code helps them understand what might be going wrong without needing to dive into the third-party codebase.

3. Efficiency: This feature saves time by reducing the need to manually locate and open files to see the relevant lines of code. It streamlines the debugging process and helps developers focus on solving the problem.

[ndmanvar]

minor clarification:
I believe we show context_lines/source_code for in-app frames; it seems like we aren't doing so for vendor-libraries (i.e, non-in-app-frames)

Also, we may shown context_lines for all frames at some point...
See following event from v5.7.0 which shows that context-lines/source_code for all frames

[sl0thentr0py]

we already support this since forever

sentry-ruby/sentry-ruby/lib/sentry/interfaces/stacktrace.rb

Lines 65 to 66 in a9b3687

	@pre_context, @context_line, @post_context = \
	linecache.get_file_context(abs_path, lineno, context_lines)

but it is true that some vendor frames are missing context lines in the final product, I will investigate why this is happening.

[sl0thentr0py]

alright, not technically a regression on our end but at some point rails added this default backtrace gem path cleaner
https://github.com/rails/rails/blob/a8709e6ea26eca73a652af4fdd0a9f7db5352af4/activesupport/lib/active_support/backtrace_cleaner.rb#L118-L125

that causes our source code reading to fail since instead of paths like

/Users/neel/.asdf/installs/ruby/3.2.6/lib/ruby/gems/3.2.0/gems/actionpack-7.1.2/lib/abstract_controller/base.rb

we get paths like

activesupport (7.1.2) lib/active_support/callbacks.rb

I will think of the best way to fix this since technically this affects all grouping now if I suddenly remove that gem filter..

[sl0thentr0py]

in the meantime, if they want to fix this, they can turn off the backtrace_cleaner with

Sentry.init do |config|
  # ...
  config.backtrace_cleanup_callback = ->(x) { x }
end