Feature: Add devcontainer support for plugin development

[Siddhi-agg]

1. Does this PR affect any open issues?(Y/N) and add issue references (e.g. "fix #123", "re #123".):

• N
• Y
  fix [Feature] add devcontainer support for plugin development #16

2. What is the scope of this PR (e.g. component or file name):

.devcontainer/Dockerfile
.devcontainer/devcontainer.json

3. Provide a description of the PR(e.g. more details, effects, motivations or doc link):

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Other

4. Are there any breaking changes?(Y/N) and describe the breaking changes(e.g. more details, motivations or doc link):

• N
• Y

5. Are there test cases for these changes?(Y/N) select and add more details, references or doc links:

• Unit test
• Integration test
• Benchmark (add benchmark stats below)
• Manual test (add detailed scripts or steps below)
• Other

[Siddhi-agg]

Hi @Peefy @amyXia1994 and team,
I tried to build a codespaces environment using this current .devcontainer configuration and I was able to build with gradle using ./gradlew build, but the ./gradlew runIde would not work. I think that the Codespaces don't allow GUI features to run in the environment after trying multiple times.

I tried to configure the project using the "Gradle for Java" extension in VSCode and then tried to runIde using that which failed (although build was successful). I also tried to setup Intellij IDEA using VSCode but wasn't able to do it because GUI wasn't supported.

PTAL at my approach and lmk if you want any changes!