[Ruby] generated client contains syntax errors when pattern of properties includes single-quote

Description

When enum has an option including an odd number of single quotes, the generated Ruby client code contains syntax errors.

Swagger-codegen version

$ java -jar modules/swagger-codegen-cli/target/swagger-codegen-cli.jar version
2.4.2-SNAPSHOT

$ git log --oneline -n 1
c4c5c062c Merge pull request #9080 from swagger-api/update-parser-v1

Swagger declaration file content or url

See: https://gist.github.com/autopp/e707d5d2ec36f7cfe6a3950d76d54b6f#file-swagger-yml

The point to notice in this example is that ' is included in the pattern constraint of the property y of the model x.

Command line used for generation

java -jar modules/swagger-codegen-cli/target/swagger-codegen-cli.jar generate -i '' -l ruby -o /tmp/gem

Steps to reproduce

1. Run the above command to generate client code for Ruby.
2. Run ruby -c /tmp/gem/lib/swagger_client/models/x.rb to check syntax of the generated model code.
3. Get errors in lib/swagger_client/models/x.rb:

/tmp/gem/lib/swagger_client/models/x.rb:51: syntax error, unexpected '.'
...ust conform to the pattern /'/.')
...                              ^
/tmp/gem/lib/swagger_client/models/x.rb:60: syntax error, unexpected ')'
...y.nil? && @y !~ Regexp.new(/'/)
...                              ^
/tmp/gem/lib/swagger_client/models/x.rb:68: syntax error, unexpected '.'
...ust conform to the pattern /'/.'
...                              ^
/tmp/gem/lib/swagger_client/models/x.rb:198: unterminated string meets end of file
/tmp/gem/lib/swagger_client/models/x.rb:198: syntax error, unexpected end-of-input, expecting keyword_end

Related issues/PRs

#9092 is similar probrem.

Suggest a fix/enhancement

escapeText of RubyClientCodegen seems to escape for double-quote string literals.
However, the corresponding template uses a single quote string. (Ruby allows both styles)
I think it is difficult for the generator to determine whether the expansion destination is a single-quote string or a double-quote string. Instead, I think that it is better to unify it with a double-quote string in the template.

I'll try and get a PR going.

Start with RubyClientCodegen.escapeText and the Ruby model template that generates x.rb. Reproduce the issue using the provided Swagger declaration and generation command, then run ruby -c on the generated model; done means a pattern containing a single quote produces syntactically valid Ruby.