feat: support escaped dollar sign in CYPRESS_DOWNLOAD_PATH_TEMPLATE

[amoshydra]

• Closes Inconsistencies in CYPRESS_DOWNLOAD_PATH_TEMPLATE handling #19914

User facing changelog

Support escaped dollar sign in CYPRESS_DOWNLOAD_PATH_TEMPLATE

Additional details

Related:

• Inconsistencies in CYPRESS_DOWNLOAD_PATH_TEMPLATE handling #19914
• feat: support alternative replace string for CYPRESS_DOWNLOAD_PATH_TEMPLATE  #19841

To support usage of CYPRESS_DOWNLOAD_PATH_TEMPLATE in npmrc in npm@6

How has the user experience changed?

User will be able to use one of these in npmrc in npm@6

CYPRESS_DOWNLOAD_PATH_TEMPLATE=\${endpoint}/\${platform}-\${arch}/cypress.zip
CYPRESS_DOWNLOAD_PATH_TEMPLATE="\${endpoint}/\${platform}-\${arch}/cypress.zip"

PR Tasks

• Have tests been added/updated?
• Has the original issue (or this PR, if no issue exists) been tagged with a release in ZenHub? (user-facing changes only)
• Has a PR for user-facing changes been opened in cypress-documentation? docs: add usage of CYPRESS_DOWNLOAD_PATH_TEMPLATE in npmrc cypress-documentation#4397
• [na] Have API changes been updated in the type definitions?
• [na] Have new configuration options been added to the cypress.schema.json?

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[CLAassistant]

All committers have signed the CLA.

[mjhenkes]

This looks good to me, thank you for the PR and the detailed investigation!