build: use a local npm registry for app packaging

[kittaakos]

Motivation

• Speed up the build by eliminating the copy phase (this change does not affect the app signing or the ZIP structure modification part, solely the build by saving time with a filesystem copy and a yarn install),
• Simplify the packager by getting rid of the file: local path (the arduino-ide-extension npm package can be picked up from the private npm registry),
• Update to lerna@6.1.0 (this change should help IDE2 to keep up with Theia and eliminates various dependabot alerts),
• Fix incorrect electron imports in the code (electron must not be imported directly but from @theia/core/electron-shared),
• Remove unnecessary electron-builder resolutions for yarn (no need for it with the @theia/*@1.3.1 version), and
• Lint the app packager code (it belongs to the IDE2's code base).

Change description

Other information

• (this change does not affect the app signing or the ZIP structure modification part, solely the build),

Package time on ubuntu from

• the main is 9m 13s,
• this PR is 8m 37s.

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This PR should not change the IDE2 behavior.

Reviewer checklist

• PR addresses a single concern.
• The PR has no duplicates (please search among the Pull Requests before creating one)
• PR title and description are properly filled.
• Docs have been added / updated (for bug fixes / features)

[kittaakos]

Other information

• (this change does not affect the app signing or the ZIP structure modification part, solely the build),

Package time on ubuntu from

• the main is 9m 13s,
• this PR is 8m 37s.

To be fair, the build times cannot be compared because they contain the npm, Open VSX, S3, and other remote requests and the app signing time...