Remove powershell

Previously, the agent plugin and part of the extension were written in
powershell. Both have since be rewritten in Rust, making ci and the
scripts themselve redundant.

We have sofar "archived" most scripts. However, being able to easily
look up these scripts offers little benefit. Having them in the git
log should suffice. Thus, we delete them.

We also remove the corresponding ci jobs.

CMK-14887

ci

@@ -4,7 +4,6 @@ main() {
 	topdir="$(git rev-parse --show-toplevel)"
 	self="${topdir}/ci"
 	cargo_toml_path="${topdir}/v2/robotmk/Cargo.toml"
-	checkmk_extensions_dir="${topdir}/checkmk_extensions"
 	mode="${1}"
 	shift
 
@@ -21,34 +20,13 @@ main() {
 		cargo test --manifest-path "${cargo_toml_path}" --all-targets
 		;;
 
-	'PSScriptAnalyzer-check-all')
-		pwsh_output=$(pwsh -Command "Invoke-ScriptAnalyzer -Settings ${topdir}/PSScriptAnalyzerSettings.psd1 -Path ${checkmk_extensions_dir} -Recurse")
-		pwsh_exitcode="$?"
-		if [ "${pwsh_exitcode}" -eq 0 ]; then {
-			if [ -z "${pwsh_output}" ]; then {
-				echo "No static Powershell issues found"
-				return 0
-			} else {
-				echo "${pwsh_output}"
-				return 1
-			}
-			fi
-		} else {
-			echo "${pwsh_output}"
-			return "${pwsh_exitcode}"
-		}
-		fi
-		;;
-
 	'check-all')
 		exit_code=0
 		for rust_step in fmt-check clippy test
 		do
 			"${self}" "cargo-${rust_step}"
 			exit_code=$(( exit_code + $? ))
 		done
-		"${self}" "PSScriptAnalyzer-check-all"
-		return "$(( exit_code + $? ))"
 		;;
 
 	*)