csolution run creates all contexts, even when just one context is selected

[ReinhardKeil]

Describe the bug

The csolution run command creates all contexts, even when just one context is selected. This may create unexpected errors that are hard to understand.

To Reproduce

• Use this example: Network.zip
• Ensure that the mbedTLS pack is not installed and execute:
• Execute:

>  csolution run c:\Test\Nov20\Network\Network.csolution.yml -g CubeMX -c BSD_Client.Debug+STM32F746NGHx
error csolution: no component was found with identifier 'Security:mbed TLS'
C:/Test/Nov20/Network/HTTPS_Server/HTTPS_Server.cproject.yml - warning csolution: dependency validation for context 'HTTPS_Server.Debug+STM32F746NGHx' failed:
MISSING Keil::Network&MDK:Service:Web Server Compact&[email protected]
  require Security:mbed [email protected]

Expected behavior

I propose that only the specified context is generated when using the run command.

Environment (please complete the following information):

• Windows
• CMSIS-Toolbox 2.6.1

[brondani]

Note that all contexts need to be processed in order to find siblings, in other words contexts sharing the same generator id, base-dir and cgen-file.
This is along the lines with what has been discussed in #1812 and ARM-software/vscode-cmsis-csolution#121.