feat: add ftl build command

[wesbillman]

Fixes #597

This currently only supports building kotlin modules. go support will be added in the future.

I'm not 100% sure if this is the best way to activate hermit as part of the build but we can discuss.

Create new module and build:

ftl init kotlin services alice

ftl build services/ftl-module-alice
info: Building kotlin module 'alice'
info: Using build command 'source ../bin/activate-hermit && mvn compile'

With log-level=debug

ftl build services/ftl-module-alice --log-level=debug
info: Building kotlin module 'alice'
info: Using build command 'source ../bin/activate-hermit && mvn compile'
debug: ../bin/activate-hermit: line 61: /bin/hermit: No such file or directory
debug: ../bin/activate-hermit: line 20: /bin/hermit: No such file or directory
debug: Hermit environment  activated
debug: [INFO] Scanning for projects...
debug: [INFO]
debug: [INFO] ------------------------< ftl:ftl-module-alice >------------------------
debug: [INFO] Building ftl-module-alice 1.0-SNAPSHOT
debug: [INFO] --------------------------------[ jar ]---------------------------------
debug: [INFO]
debug: [INFO] --- maven-dependency-plugin:3.2.0:copy (default) @ ftl-module-alice ---
debug: [INFO] Configured Artifact: xyz.block:ftl-generator:jar-with-dependencies:1.0-SNAPSHOT:jar

Default build command can be overridden in ftl.toml

module = "alice"
language = "kotlin"
build = "source ../bin/activate-hermit && mvn clean compile"
deploy = [
  "target/main",
  "target/classes",
  "target/dependency",
  "target/classpath.txt",
]

ftl build services/ftl-module-alice
info: Building kotlin module 'alice'
info: Using build command 'source ../bin/activate-hermit && mvn clean compile'

Example errors:

Building a go module:

ftl build echo
ftl: error: unable to build. unknown language "go"

toml not found

ftl build bogus
ftl: error: [<base>]: stat /Users/wesbillman/dev/ftl/examples/bogus: no such file or directory

[alecthomas]

Glorious!

Weird that the Hermit activation is throwing an error...

[alecthomas]

You'll have to check if the ../bin/hermit directory exists, as it's optional.

[alecthomas]

Actually I would remove the Hermit activation completely. We should assume that the user has either already activated the environment, or isn't using it.

[wesbillman]

Yeah I was curious about that. In our "default" build would we assume it's there? Or, should I just always check if there is one and if so go ahead and add the activation?