Add Ballerina metrics logs observer

[NipunaMadhushan]

Purpose

We are implementing log based metrics for Ballerina as a requirement for all WSO2 on-prem and SaaS products that need to use the same stack for observability. In order to retrieve metrics data using OpenSearch, we need to provide log based metrics which contain a format as follows.

[Time Stamp] protocol:<protocol_type> tagKey1:tagValue1 tagKey2:tagValue2 .. response_time:<value_in_seconds>

Fixes #43614

Approach

Describe how you are implementing the solutions along with the design details.

Samples

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Remarks

List any other known issues, related PRs, TODO items, or any other notes related to the PR.

Check List

• Read the Contributing Guide
• Updated Change Log
• Checked Tooling Support (#)
• Added necessary tests
  • Unit Tests
  • Spec Conformance Tests
  • Integration Tests
  • Ballerina By Example Tests
• Increased Test Coverage
• Added necessary documentation
  • API documentation
  • Module documentation in Module.md files
  • Ballerina By Examples

[warunalakshitha]

License text missing

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 77.42%. Comparing base (fb27ea2) to head (70ee310).
Report is 101 commits behind head on master.

Files with missing lines	Patch %	Lines
.../ballerina/runtime/observability/ObserveUtils.java	50.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #43615      +/-   ##
============================================
- Coverage     77.47%   77.42%   -0.06%     
- Complexity    58512    58576      +64     
============================================
  Files          3434     3443       +9     
  Lines        218711   218978     +267     
  Branches      28918    28957      +39     
============================================
+ Hits         169443   169536      +93     
- Misses        39874    40023     +149     
- Partials       9394     9419      +25     

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