patternMatcher.severity can only have for value "error|warning|info".
This is too restrictive for all the possible values from our tools.
As a workaround create 3 patternMatcher for each of the level.
Add a test
Closes eng/ide/ada_language_server#784
This allows to have access to their Registers and Disassembly
views now that Ada has been added to the supported languages.
Modify the extension's walkthrough accordingly.