Avoid taking unnecessary ownership of intermediates (#12740)

# Description

Judiciously try to avoid allocations/clone by changing the signature of
functions

- **Don't pass str by value unnecessarily if only read**
- **Don't require a vec in `Sandbox::with_files`**
- **Remove unnecessary string clone**
- **Fixup unnecessary borrow**
- **Use `&str` in shape color instead**
- **Vec -> Slice**
- **Elide string clone**
- **Elide `Path` clone**
- **Take &str to elide clone in tests**

# User-Facing Changes
None

# Tests + Formatting
This touches many tests purely in changing from owned to borrowed/static
data

tests/plugins/formats/ics.rs

@@ -6,7 +6,7 @@ use pretty_assertions::assert_eq;
 #[test]
 fn infers_types() {
     Playground::setup("filter_from_ics_test_1", |dirs, sandbox| {
-        sandbox.with_files(vec![FileWithContentToBeTrimmed(
+        sandbox.with_files(&[FileWithContentToBeTrimmed(
             "calendar.ics",
             r#"
                 BEGIN:VCALENDAR
@@ -58,7 +58,7 @@ fn infers_types() {
 #[test]
 fn from_ics_text_to_table() {
     Playground::setup("filter_from_ics_test_2", |dirs, sandbox| {
-        sandbox.with_files(vec![FileWithContentToBeTrimmed(
+        sandbox.with_files(&[FileWithContentToBeTrimmed(
             "calendar.txt",
             r#"
                 BEGIN:VCALENDAR
@@ -102,7 +102,7 @@ fn from_ics_text_to_table() {
 #[test]
 fn from_ics_text_with_linebreak_to_table() {
     Playground::setup("filter_from_ics_test_3", |dirs, sandbox| {
-        sandbox.with_files(vec![FileWithContent(
+        sandbox.with_files(&[FileWithContent(
             "calendar.txt",
             r#"BEGIN:VCALENDAR
 BEGIN:VEVENT