feat(typescript-angular): prepare build

[evanjmg]

Prepare build is required in order to publish

PR checklist

• [X ] Read the contribution guidelines.
• [ X] Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• [X ] Run the following to build the project and update samples:

  ./mvnw clean package 
  ./bin/generate-samples.sh
  ./bin/utils/export_docs_generators.sh
  

  Commit all changed files.
  This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master.
  These must match the expectations made by your contribution.
  You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/java*.

[fredericrous]

without the "prepare" step, the package that is published does not contain the built artefact. we are just publishing the sources.

The other generators already implement the prepare step
example:

• openapi-generator/modules/openapi-generator/src/main/resources/typescript-rxjs/package.mustache

  Line 14 in 5221ca2

  "prepare": "npm run build"

• openapi-generator/modules/openapi-generator/src/main/resources/typescript-axios/package.mustache

  Line 22 in 5221ca2

  "prepare": "npm run build"

• openapi-generator/modules/openapi-generator/src/main/resources/typescript-aurelia/package.json.mustache

  Line 20 in 5221ca2

  "prepare": "npm run build",

• openapi-generator/modules/openapi-generator/src/main/resources/typescript-fetch/package.mustache

  Line 22 in 5221ca2

  "prepare": "npm run build"{{/sagasAndRecords}}

[macjohnny]

can you please re-generate the samples?

[wing328]

merged via #21684

thanks for the pr