[SystemMonitor] Port detailed memory information to QtWidgets

Currently, the detailed memory information is displayed as a web page, and this has several limitations:

• it's not possible to filter data
• it's not possible to sort data by a specific column
• it's not possible to move columns
• it's quite slow and looks outdated

Porting it to QtWidgets removes these limitations and adds new features:

• general page: shows general information about process
• memory maps page: shows memory consumption for each of the process's mappings
• open files: shows files opened by the process