Add support for partial checkout filters (#1396)

* added filter option & tests

* added build file

* fix test oversight

* added exit 1

* updated docs to specify override

* undo unneeded readme change

* set to undefined rather than empty string

* run git config in correct di

---------

Co-authored-by: Cory Miller <13227161+cory-miller@users.noreply.github.com>

src/input-helper.ts

@@ -82,6 +82,14 @@ export async function getInputs(): Promise<IGitSourceSettings> {
   result.clean = (core.getInput('clean') || 'true').toUpperCase() === 'TRUE'
   core.debug(`clean = ${result.clean}`)
 
+  // Filter
+  const filter = core.getInput('filter')
+  if (filter) {
+    result.filter = filter
+  }
+
+  core.debug(`filter = ${result.filter}`)
+
   // Sparse checkout
   const sparseCheckout = core.getMultilineInput('sparse-checkout')
   if (sparseCheckout.length) {