feat: Change default preprocessor to webpack

[chrisbreiding]

• Closes Typescript support: support / load user defined tsconfig.json for transpiling files #7006
• Closes Cypress cannot start with importHelpers and allowJS TypeScript options #7503

User facing changelog

• Cypress now uses the webpack preprocessor by default to preprocess spec files.
• For TypeScript projects, tsconfig.json will now be loaded and used to configure TypeScript compilation of spec and support files.
• BREAKING CHANGE: Cypress no longer supports file paths with a question mark (?) in them (because webpack does not support files with question marks).

PR Tasks

• Have tests been added/updated?
• Has the original issue been tagged with a release in ZenHub?
• Has a PR for user-facing changes been opened in cypress-documentation? Update default preprocessor references from browserify to webpack cypress-documentation#3015
• N/A Have API changes been updated in the type definitions?
• N/A Have new configuration options been added to the cypress.schema.json?

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[cypress]

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Test summary

7957 • 0 • 108 • 2

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Run details

Project	cypress
Status	Passed
Commit	80ee0f7
Started	Aug 10, 2020 8:26 PM
Ended	Aug 10, 2020 8:33 PM
Duration	06:59 💡
OS	Linux Debian - 10.2
Browser	Multiple

View run in Cypress Dashboard ➡️

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[sync-by-unito]

➤ Chris Breiding commented:

This is a PR. I don’t think it should be in Jira, should it?

[chrisbreiding]

The failing tests seem to be from the upstream 5.0 branch.