impl: check if the cli exists before running it to spill out the version

The logic for matching the local CLI version with the deployment previously attempted to run
the CLI with --version without first verifying that the binary existed. This commit improves
that by first checking if the file exists, avoiding the unnecessary overhead of spawning a
process for a non-existent binary.

Author: fioan89

src/main/kotlin/com/coder/toolbox/cli/CoderCLIManager.kt

@@ -489,6 +489,7 @@ class CoderCLIManager(
      * version could not be parsed.
      */
     fun matchesVersion(rawBuildVersion: String): Boolean? {
+        if (Files.notExists(localBinaryPath)) return null
         val cliVersion = tryVersion() ?: return null
         val buildVersion =
             try {