Browser detection removal

[AaronDabney]

The inner browser check and isBrowser util can be factored out
lib/common/lib/headers.ts
lib/common/lib/utils.ts

export function addUserAgent(headers: Headers) {
  const appendUserAgent = process.env.OCI_SDK_APPEND_USER_AGENT;
  const clientInfo = `Oracle-TypeScriptSDK/${version}`;

  // Check if the sdk is used in browser or node, populate header accordingly.
  if (!isBrowser()) {
    // Hash the values of Platform specific attributes
    if (isEmpty(NODE_PLATFORM_HASH)) {
      populatePlatformHash();
    }

    const platform = NODE_PLATFORM_HASH.get(PLATFORM_KEY);
    const release = NODE_PLATFORM_HASH.get(RELEASE_KEY);
    const nodeVersion = NODE_PLATFORM_HASH.get(VERSION_KEY);

    // Formulate User-Agent
    let userAgent = appendUserAgent
      ? `${clientInfo} (${platform}/${release}; Node/${nodeVersion}) ${appendUserAgent}`
      : `${clientInfo} (${platform}/${release}; Node/${nodeVersion})`;

    // Headers will always be replaced if they exist already
    headers.append(USER_AGENT_HEADER, userAgent);
    return;
  }
  headers.append(BROWSER_USER_AGENT_HEADER, clientInfo);
}

PR to follow