Automate bootstrap.properties LSP tests and refactor server.env into shared suite

[sharma1208]

Closes: #438

Description:

This PR implements automated UI tests for Liberty Language Server support in bootstrap.properties, and refactors the existing server.env tests to eliminate duplication via a shared test suite.

New: bootstrap.properties test coverage
Adds MavenBootstrap.ts covering the three LSP features called out in #438:

1. Hover (Tests liberty-ls Hover support in bootstrap.properties for a Liberty Server properties setting #425 ) verifies hover documentation for com.ibm.ws.logging.log.directory and com.ibm.ws.logging.message.format
2. Completion (Tests liberty-ls type ahead support in bootstrap.properties for a Liberty Server Configuration booststrap.properties entry #423 ) types com.ibm.ws.logging.con, selects com.ibm.ws.logging.console.log.level from the completion list, and appends =INFO
3. Diagnostic + quick fix (Tests liberty-ls diagnostic support in boostrap.properties #426 ) replaces the valid value with INVALID, asserts the error marker appears, applies the quick fix, and verifies the diagnostic clears

Also added the seed file bootstrap.properties to the Maven test project with relative paths

Refactor: shared configFileTestSuite
Both server.env and bootstrap.properties follow the exact same test structure (2 hovers, 1 completion, 1 diagnostic+quickfix). Extracted into src/test/shared/configFileTestSuite.ts as a fully parameterized runConfigFileTestSuite() function.