feat: add config property to set trace level

[nikpivkin]

This PR adds the ability to set the trace level for intercepting requests and responses between client and server.

[Trace - 01:54:39] Sending request 'initialize - (0)'.
Params: {
    "processId": 91401,
    "clientInfo": {
        "name": "Visual Studio Code",
        "version": "1.92.1"
    },
    "locale": "en",
    "rootPath": "/Users/.../projects/rego-lsp-test",
    "rootUri": "file:///Users/.../projects/rego-lsp-test",
    "capabilities": {
        "workspace": {
            "applyEdit": true,
            "workspaceEdit": {
                "documentChanges": true,
                "resourceOperations": [
                    "create",
                    "rename",
                    "delete"
                ],
...

[charlieegan3]

This looks positive, I think it looks too like we might be able to replace

vscode-opa/src/ls/clients/regal.ts

Line 120 in bc2404b

if (process.env.VSCODE_DEBUG_MODE === 'true') {

with this - but only once we have the Regal LS side to this too?

Do we not need to send/set this config as part of the initialisation options too? (i.e. in here somewhere: https://github.com/open-policy-agent/vscode-opa/blob/main/src/ls/clients/regal.ts#L167)