Replace handlebars with string replace

Not a big deal, but I think we could replace handlebars with a few string replaces or a custom function that handles it.

$ cargo bloat --release --crates

 File  .text     Size Crate
12.9%  43.4% 367.8KiB std
 7.6%  25.5% 216.2KiB handlebars
 3.5%  11.8%  99.7KiB tokio
 1.6%   5.5%  46.8KiB dprint_plugin_exec
 1.3%   4.2%  35.8KiB serde_json
 0.8%   2.6%  21.7KiB dprint_core
 0.5%   1.7%  14.2KiB parking_lot
 0.3%   1.1%   9.5KiB serde
 0.2%   0.8%   6.9KiB pest
 0.2%   0.7%   6.1KiB num_cpus
 0.1%   0.4%   3.5KiB anyhow
 0.1%   0.3%   2.5KiB parking_lot_core
 0.1%   0.2%   1.9KiB [Unknown]
 0.1%   0.2%   1.5KiB signal_hook_registry
 0.0%   0.2%   1.3KiB once_cell
 0.0%   0.1%   1.2KiB splitty
 0.0%   0.1%   1.1KiB memchr
 0.0%   0.0%     430B smallvec
 0.0%   0.0%     310B mio
29.6% 100.0% 848.1KiB .text section size, the file size is 2.8MiB

After:

$ cargo bloat --release --crates

 File  .text     Size Crate
13.1%  58.2% 324.5KiB std
 4.0%  17.8%  99.4KiB tokio
 1.5%   6.5%  36.2KiB dprint_plugin_exec
 0.9%   4.2%  23.4KiB serde_json
 0.9%   4.0%  22.4KiB dprint_core
 0.6%   2.5%  14.2KiB parking_lot
 0.4%   1.7%   9.5KiB serde
 0.2%   1.1%   6.1KiB num_cpus
 0.1%   0.6%   3.5KiB anyhow
 0.1%   0.4%   2.5KiB parking_lot_core
 0.1%   0.3%   1.9KiB [Unknown]
 0.1%   0.3%   1.6KiB signal_hook_registry
 0.1%   0.2%   1.3KiB once_cell
 0.0%   0.2%   1.2KiB splitty
 0.0%   0.2%   1.1KiB memchr
 0.0%   0.1%     430B smallvec
 0.0%   0.1%     310B mio
22.4% 100.0% 557.1KiB .text section size, the file size is 2.4MiB

dprint / dprint-plugin-exec

Replace handlebars with string replace #6