Add a vendordep gradle task

[Starlight220]

Fixes #417
The original commit uses curl, the second uses the gradle-download plugin.

[Starlight220]

How do I test the "feature" I added?

[ThadHouse]

Bump the version number, run the publishToMavenLocal task, and then use that updated version number in a normal robot project.

[Starlight220]

Fixed.

[ThadHouse]

@Starlight220 looks good. Can you do a few things though. The first 2 before I'll merge it, the third just make a plan to do.

1. Update the download task to the latest version (its been updated)
2. Instead of just printing an error, also add an example of how to pass a url. Gradle doesn't print this by default, but for our users it'd be really helpful. Something like "No vendor JSON URL was entered. Try the following \n.\gradlew vendordep --url <insert_url_here>"
3. Work with @Daltz333 to get something added to docs for this.

[Starlight220]

3 is already done, it's waiting for this to be merged. The frc-docs PR is linked above.
Will do 1,2 soon
Done, ready for review.

[Starlight220]

@ThadHouse - I finished 1,2. Feel free to review/merge/whatever. 3 is wpilibsuite/frc-docs#755, feel free to check it out.

[Starlight220]

@ThadHouse - I was thinking about special-casing two strings in the task so that teams can use this task also to get the Command-Based JSONs with the task. maybe something like gradlew vendordep --url=$COMMAND-NEW. Preferably the first char would be an uncommon character ($ % & etc) so that it's a single char comparison to check if we have a URL or a special case (and if it's the latter we then check if the special case is valid etc).
This would be helpful because right now there isn't a conventional way to get the command-based JSONs.

Either way, I think this feature would be more appropriate as a separate PR, assuming you think it should be added at all - what are your thoughts about this. All your reviews of this PR are fixed, can you review/merge it?

[ThadHouse]

How would that help. A user could just use the git url directly and pass it it. Definitely opposed to embedding that url in gradlerio, which is what it would take.

And there is a conventional way to get the command based json. VS Code, and theyre always installed with the installer.

[Starlight220]

I was more thinking about it fetching the JSON from the local wpi maven repo (where VS Code fetches it from anyway).

[Starlight220]

@ThadHouse should I add some docs about this to the Adding Vendor Dependencies - Without VS Code section in the README.md?

[ThadHouse]

Regarding the local url, if its just pointing to the local folder, I'm not opposed. Something like $FRCLOCAL\filename.json Just make sure its using starts with to make sure that only matches in the beginning.

[ThadHouse]

And yes, updating the readme would be helpful.

[Starlight220]

I finally got the local fetching to work.
Needs some testing. I'll be testing these cases, extra cases are welcome:

• make sure info prints are correct
• no URL passed {fails with usage error message}

Local

• 1. exists in FRCHOME, nonexistent in project, default vendor folder location {should add the file}
• 2. nonexistent in FRCHOME, nonexistent in project, default vendor folder location {should fail with file not found error message}
• 3. exists in FRCHOME, existent in project, default vendor folder location {should replace with warning/message}
• 4. same as (1) but non-default vendor folder location
• 5. same as (2) but non-default vendor folder location
• 6. same as (3) but non-default vendor folder location
• finds $FRCLOCAL only if it's at the beginning of the URL string {failed with an exception from the web access code}

Remote

• valid URL, default folder location
• invalid URL, default folder location
• valid URL, nondefault folder location
• invalid URL, nondefault folder location

[Starlight220]

I now tested, the only issue I saw was that the overwriting warning isn't printed when fetching from remote.