Simplify the defaults for the typical case

[wilkinsona]

It appears to be typical to use configuration like this:

url: ${{ env.OSSRH_URL }}
username: ${{ secrets.OSSRH_S01_TOKEN_USERNAME }}
password: ${{ secrets.OSSRH_S01_TOKEN_PASSWORD }}
staging-profile-name: ${{ secrets.OSSRH_STAGING_PROFILE_NAME }}
create: true
upload: true
generate-checksums: true
upload-parallel: 10
close: true
release: true

The above can be seen in @abilan's workflows. Spring Shell has very similar configuration as well.

#4 removed the need to configure the URL when using s01. Could similar updates to the other defaults be made as well? Specifically, I would welcome all of the following defaulting to true:

• close
• create
• generate-checksums
• release
• upload

Combined with #4, this would reduce the configuration above to the following:

username: ${{ secrets.OSSRH_S01_TOKEN_USERNAME }}
password: ${{ secrets.OSSRH_S01_TOKEN_PASSWORD }}
staging-profile-name: ${{ secrets.OSSRH_STAGING_PROFILE_NAME }}
upload-parallel: 10