Escape typeprefix

[cuminandpaprika]

Fixes the escaping of special chars which was previously causing syntax errors.

e.g the following OpenAPI input would produce invalid Sysl due to special characters not being escaped

 /withHeaders:andSpecialChars:
    get:
      responses:
        200:
          description: "200 OK"
          content:
            application/json:
              schema:
                $ref: "#/components/schemas/SimpleObj"
        404:
          description: "Not Found"
          headers:
            content-type:
              type: string
          content:
            application/json:
              schema:
                $ref: "#/components/schemas/Error"

Changes proposed in this pull request:

• Add escaping of special characters in the OpenAPI3 importer, when responses have a header field defined
• Add updating of importer test files to make golden target

Checklist:

• Added related tests
• Made corresponding changes to the documentation

[codecov]

Codecov Report

Merging #952 into master will increase coverage by 0.78%.
The diff coverage is 83.88%.

@@            Coverage Diff             @@
##           master     #952      +/-   ##
==========================================
+ Coverage   83.35%   84.14%   +0.78%     
==========================================
  Files          73       74       +1     
  Lines       10609    10309     -300     
==========================================
- Hits         8843     8674     -169     
+ Misses       1432     1322     -110     
+ Partials      334      313      -21     

Impacted Files	Coverage Δ
pkg/pbutil/output.go	76.00% <ø> (-0.48%)	⬇️
pkg/syslwrapper/test_helper.go	57.89% <ø> (-1.42%)	⬇️
pkg/parse/listener_impl.go	89.50% <61.53%> (+<0.01%)	⬆️
pkg/importer/importer.go	63.15% <63.15%> (ø)
pkg/mod/gomod.go	73.68% <66.66%> (+1.27%)	⬆️
pkg/parse/parse.go	83.47% <69.56%> (-0.50%)	⬇️
pkg/mod/module.go	66.66% <72.72%> (+0.95%)	⬆️
pkg/importer/formats.go	77.27% <77.27%> (ø)
pkg/importer/openapi.go	81.73% <80.71%> (-7.72%)	⬇️
pkg/importer/swagger.go	81.48% <88.88%> (+1.88%)	⬆️
... and 16 more

[andrewemeryanz]

Good.