Add initial test preparing "--force-exclude"

Author: Delgan

crates/typos-cli/tests/cmd/force-exclude.in/_typos.toml

@@ -0,0 +1,5 @@
+[files]
+extend-exclude = ["file.ignore"]
+
+[default.extend-identifiers]
+hello = "goodbye"

crates/typos-cli/tests/cmd/force-exclude.in/file.ignore

@@ -0,0 +1 @@
+hello

crates/typos-cli/tests/cmd/force-exclude.toml

@@ -0,0 +1,13 @@
+bin.name = "typos"
+args = "file.ignore"
+stdin = ""
+stdout = """
+error: `hello` should be `goodbye`
+  --> file.ignore:1:1
+  |
+1 | hello
+  | ^^^^^
+  |
+"""
+stderr = ""
+status.code = 2