Add Optional skipNpmrc input

[JP-Dhabolt]

As part of trying to use this action for a private Azure DevOps Artifact Feed (where the .npmrc file uses username and _password instead of _authToken), I ran into the issue where the file was always modified by the action.

This PR adds an optional input called skipNpmrc which simply bypasses any checks, creation, or update of the .npmrc file. Not including the new input continues to behave exactly as it does today.

None of the code in the new createOrUpdateNpmrc function was modified, just extracted into the function.

While I am unblocked since I am running the action successfully now from the fork, I thought this might be generally useful if others have the same problem. If this is not in line with your vision of the action, please feel free to close. No hard feelings. 😄

[changeset-bot]

🦋 Changeset detected

Latest commit: 2c90823

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@changesets/action	Minor

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[jameslnewell]

This would benefit our use case with AWS CodeArtifact too.

We have a .npmrc file that contains

@scope:registry=https://abcd.d.codeartifact.ap-southeast-2.amazonaws.com/npm/npm/
//abcd.d.codeartifact.ap-southeast-2.amazonaws.com/npm/npm/:_authToken=XXXX

And changesets is overwriting .npmrc to contain

//registry.npmjs.org/:_authToken=undefined

[JP-Dhabolt]

@jameslnewell If you update your workflow that references this action to uses: JP-Dhabolt/changesets-action@skip-npmrc-compiled, it should act as a workaround until this gets merged in.