chore: fix prepublish script inconsistencies

[tido64]

Summary:

Addresses inconsistencies in the prepublish script by moving the Azure Pipelines checks after the correct tag has been determined.

Test Plan:

Ensure tag is correctly set on main:

~/S/react-native-macos (main) % node .ado/scripts/prepublish-check.mjs --verbose
❌ .ado/templates/npm-publish-steps.yml: 'publishTag' needs to be set to 'nightly'

Ensure tag is correctly set for 0.76-stable (previous):

~/S/react-native-macos (0.76-stable) % node .ado/scripts/prepublish-check.mjs --verbose
ℹ️ react-native-macos@latest: 77
ℹ️ Current version: 76
ℹ️ Expected npm tag: v0.76-stable
❌ 'release.version.generatorOptions.currentVersionResolverMetadata.tag' must be set to 'v0.76-stable'
❌ Nx Release is not correctly configured for the current branch

Ensure tag is correctly set for 0.77-stable (current):

~/S/react-native-macos (0.77-stable) % node .ado/scripts/prepublish-check.mjs --verbose
ℹ️ react-native-macos@latest: 77
ℹ️ Current version: 77
ℹ️ Expected npm tag: latest
##vso[task.setvariable variable=publish_react_native_macos]1

Ensure tag is correctly set for 0.78-stable (release candidate):

~/S/react-native-macos (0.78-stable) % node .ado/scripts/prepublish-check.mjs --verbose
ℹ️ react-native-macos@latest: 77
ℹ️ Current version: 78
ℹ️ Expected npm tag: next
❌ 'defaultBase' must be set to '0.78-stable'
❌ 'release.version.generatorOptions.preid' must be set to 'rc'
❌ 'release.version.generatorOptions.currentVersionResolverMetadata.tag' must be set to 'next'
❌ Nx Release is not correctly configured for the current branch

Update config for 0.78-stable (release candidate):

~/S/react-native-macos (0.78-stable) % node .ado/scripts/prepublish-check.mjs --update
❌ 'defaultBase' must be set to '0.78-stable'
❌ 'release.version.generatorOptions.preid' must be set to 'rc'
❌ 'release.version.generatorOptions.currentVersionResolverMetadata.tag' must be set to 'next'

~/S/react-native-macos (0.78-stable) [1]% node .ado/scripts/prepublish-check.mjs --verbose
ℹ️ react-native-macos@latest: 77
ℹ️ Current version: 78
ℹ️ Expected npm tag: next
❌ .ado/templates/npm-publish-steps.yml: 'publishTag' needs to be set to 'next'

Mark 0.78-stable stable:

~/S/react-native-macos (0.78-stable) % node .ado/scripts/prepublish-check.mjs --verbose --tag latest --update
ℹ️ react-native-macos@latest: 77
ℹ️ Current version: 78
ℹ️ Expected npm tag: latest
❌ 'defaultBase' must be set to '0.78-stable'

~/S/react-native-macos (0.78-stable) [1]% node .ado/scripts/prepublish-check.mjs --verbose --tag latest
ℹ️ react-native-macos@latest: 77
ℹ️ Current version: 78
ℹ️ Expected npm tag: latest
##vso[task.setvariable variable=publish_react_native_macos]1