RFR: 8263760: Update gradle to version 7.0.1

[Kevin Rushforth]

This PR fixes the gradle deprecation warnings described in [JDK-8240336](https://bugs.openjdk.java.net/browse/JDK-8240336) and updates the JavaFX build to use gradle 7.0.1 as described in [JDK-8263760](https://bugs.openjdk.java.net/browse/JDK-8263760). The minimum version of gradle is set to 6.3.

In addition to keeping gradle up to date, updating to gradle 7 will allow building and testing JavaFX with JDK 16.

I have done a full build and test on all three platforms, comparing the artifacts produced before and after this change.

### Notes to Reviewers:

The PR branch has two separate commits, one for each fix, in case reviewers want to look at them separately. As always, they will be squashed into a single commit when integrated. Both bug IDs will be listed in the commit.

The following changes were done for [JDK-8240336](https://bugs.openjdk.java.net/browse/JDK-8240336) to eliminate the use of deprecated features removed in gradle 7:

1. Replaced `compile` with either `implementation` or `compileClasspath` as needed
2. Replaced obsolete `archiveName` and `destinationDir` properties in archive tasks with `archiveFileName` and `destinationDirectory`
3. Added missing `@Input` annotation to custom Groovy task properties
4. Bumped the minimum version of gradle to 6.3 (which we have been using for more than 1 year)


The following changes were done for [JDK-8263760](https://bugs.openjdk.java.net/browse/JDK-8263760) to update to gradle 7.0.1:

1. Ran `bash ./gradlew wrapper --gradle-version=7.0.1`
2. Updated the gradle version in `build.properties` to `7.0.1`
3. Updated the SHA-256 checksum in `gradle/wrapper/gradle-wrapper.properties`

-------------

Commit messages:
 - Revert auto-generated change to DEFAULT_JVM_OPTS in gradlew scripts
 - 8263760: Update gradle to version 7.0.1
 - 8240336: JavaFX build uses deprecated features that will be removed in gradle 7

Changes: https://git.openjdk.java.net/jfx/pull/498/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=498&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8263760
  Stats: 145 lines in 13 files changed: 45 ins; 5 del; 95 mod
  Patch: https://git.openjdk.java.net/jfx/pull/498.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/498/head:pull/498

PR: https://git.openjdk.java.net/jfx/pull/498