Wrap building applet, reader and common with Nix

[quapka]

Added simple wrappers around the Gradle build targets to build via Nix. The updates in the README.md are a bit lacking.

[quapka]

• Add building the new targets to CI pipeline

[quapka]

I've tried cherry-picking 8c1bcb8, but building 2.2.1 version was failing anyways. The error was (both with ./gradlew :applet:buildJavaCard or when built via Nix):

[ant:compile] [REDACTED]/ec2/applet/src/main/java/cz/crcs/ectester/applet/EC_Consts.java:1487: warning: [fallthrough] possible fall-through into case
[ant:compile]             case X962_COMPRESSED: /* fallthrough */
[ant:compile]             ^
[ant:compile] 1 warning
[ant:convert] Verifier Error: Incorrect value of stop bit for exception handler 0

> Task :applet:buildJavaCard FAILED
[ant:cap] INFO: using JavaCard 2.2.1 SDK in [REDACTED]/ec2/ext/sdks/jc221_kit
[ant:cap] Building CAP with 1 applet from package cz.crcs.ectester.applet (AID: 4543546573746572)
[ant:cap] cz.crcs.ectester.applet.ECTesterApplet 454354657374657230333320323231
[ant:compile] Compiling files from [REDACTED]/ec2/applet/src/main/java
[ant:compile] Compiling 7 source files to /tmp/jccpro8394964778032680176

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':applet:buildJavaCard'.
> Java returned: 1

* Try:
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.
> Get more help at https://help.gradle.org.

Deprecated Gradle features were used in this build, making it incompatible with Gradle 9.0.

You can use '--warning-mode all' to show the individual deprecation warnings and determine if they come from your own scripts or plugins.

For more on this, please refer to https://docs.gradle.org/8.7/userguide/command_line_interface.html#sec:command_line_warnings in the Gradle documentation.

BUILD FAILED in 1s
1 actionable task: 1 executed

However, the 2.2.1 built successfully for me, when I used the epare branch. The changes for 2.2.1 will require updating the gradle.lock, which is produced by gradle2nix, in particular, the v2 version/branch from https://github.com/tadfisher/gradle2nix. I am using the following bash script (source from tadfisher/gradle2nix#77 (comment), with the last line removed):

# set JAVA_HOME for gradle2nix
# this is faster, but requires openjdk-21 in /nix/store
# export JAVA_HOME=$(ls -d /nix/store/*-openjdk-21* | grep -v '.drv$' | sort -V | tail -n1)
export JAVA_HOME=$(nix-build --no-out-link '<nixpkgs>' -A jdk21)

# nix run github:tadfisher/gradle2nix/v2
function gradle2nix() {
  nix run github:tadfisher/gradle2nix/v2 -- "$@"
}

[J08nY]

Can we merge this? Then epare can be merged afterwards and we can work out what is the issue with the 2.2.1.

[quapka]

Can we merge this? Then epare can be merged afterwards and we can work out what is the issue with the 2.2.1.

Yes, it can be merged.