Don't crash when nonexistent symbol is used with external inputs

[levimatheri]

Description

Below code was crashing language server due to unhandled exception when analyzing external input functions.
Updated InlineParameterRewriter to explicity throw ExpressionException so it can be caught and handled gracefully during external input analysis.

import { myVar, helperFunction } from 'main.bicep' // imported symbols don't exist in 'main.bicep'

param p12 = '${myVar}-${helperFunction()}-${externalInput('custom')}'

Checklist

• I have read and adhere to the contribution guide.

Microsoft Reviewers: Open in CodeFlow

[github-actions]

Test this change out locally with the following install scripts (Action run 23461144937)

VSCode

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-vsix.sh) --run-id 23461144937

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-vsix.ps1) } -RunId 23461144937"

Azure CLI

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-cli.sh) --run-id 23461144937

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-cli.ps1) } -RunId 23461144937"