feat(cli): fern check now confirms IR version is compatible between generator and cli

[armandobelardo]

Fixes FER-3011

This PR introduces a new feature to the Fern CLI, which checks that the generator versions you are running are compatible with your Fern CLI version. It also adds availability and display-names to discriminated union values, allowing users to mark their union values in their docs.

The PR also includes the following changes:

• A new GeneratorGroupSchema is exported from the index.ts file in the packages/cli/configuration/src/generators-yml directory.
• The @fern-api/core dependency is added to the package.json file in the packages/cli/fern-definition/validator directory.
• A new generatorInvocation type is added to the GeneratorsYmlFileAstNodeTypes interface in the GeneratorsYmlAstVisitor.ts file in the packages/cli/fern-definition/validator/src/ast directory.
• The visitGeneratorsYamlAst function in the visitGeneratorsYamlAst.ts file in the packages/cli/fern-definition/validator/src/ast directory is updated to include a new groups property, which asynchronously calls the visitGeneratorGroups function.
• A new visitGeneratorGroups function is added to the visitGeneratorGroups.ts file in the packages/cli/fern-definition/validator/src/ast/visitors directory. This function iterates over the groups object and calls the visitGeneratorGroup function for each group.
• A new createGeneratorsYmlAstVisitorForRules function is added to the createGeneratorsYmlAstVisitorForRules.ts file in the packages/cli/fern-definition/validator/src/ast directory. This function creates an AST node visitor for the file and generatorInvocation node types.
• A new CompatibleIrVersionsRule is added to the getAllRules.ts file in the packages/cli/fern-definition/validator/src/rules directory.
• A new test file, compatible-ir-versions.test.ts, is added to the packages/cli/fern-definition/validator/src/rules/compatible-ir-versions/__test__ directory. This file contains a test for the compatible-ir-versions rule.
• A new CompatibleIrVersionsRule is added to the compatible-ir-versions.ts file in the packages/cli/fern-definition/validator/src/rules/compatible-ir-versions directory. This rule checks that the generator versions are compatible with the CLI version.
• The getViolationsForRule function in the getViolationsForRule.ts file in the packages/cli/fern-definition/validator/src/testing-utils directory is updated to include a new cliVersion property in the Args interface.
• The validateFernWorkspace function in the validateFernWorkspace.ts file in the packages/cli/fern-definition/validator/src directory is updated to include a new validateGeneratorsYmlFile function, which validates the generators.yml file using the createGeneratorsYmlAstVisitorForRules and visitGeneratorsYamlAst functions.
• The @fern-fern/generators-sdk dependency is added to the package.json file in the packages/core directory.
• A new createFdrGeneratorsSdkService function is added to the fdrGeneratorsSdk.ts file in the packages/core/src/services directory. This function creates an instance of the FernRegistryClient class from the @fern-fern/generators-sdk package.
• The createFdrGeneratorsSdkService function is exported from the index.ts file in the packages/core/src/services directory.