enable read env map from KCL option("env") function

[satyazzz123]

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

fixes: #29

• [ ] N
• [x] Y

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

Read the environment var map through option("env") in KRM KCL Spec.

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

[satyazzz123]

Hello @Peefy I have opened this PR to address issue #29 , I have made some initial changes to read env map . Please have a look and suggest if any changes are needed. Thank you!

[satyazzz123]

@Peefy I have addressed the requested changes please review