Make clippy more strict

[jaytaph]

Right now we have a very open clippy policy (the default basically).. We probably want to have a more strict setting of clippy rules.

An initial idea was:

[workspace.lints.clippy]
#perf = { level = "deny", priority = -1 }
#pedantic = { level = "warn", priority = -1 }
#nursery = { level = "warn", priority = -1 }
#cargo = { level = "warn", priority = -1 }
#panic = "deny"
#unwrap_used = "deny"
clone_on_ref_ptr = "warn"
empty_enum_variants_with_brackets = "warn"
empty_structs_with_brackets = "warn"
enum_glob_use = "warn"
error_impl_error = "warn"
format_push_string = "warn"
infinite_loop = "warn"
rc_buffer = "warn"
rc_mutex = "warn"
expect_used = "warn"
missing_docs_in_private_items = "allow"
cargo_common_metadata = "allow" # should be removed if we release our crates to crates.io
cast_possible_truncation = "allow" # should this be on allow?
cast_precision_loss = "allow"
cast_sign_loss = "allow"
cast_possible_wrap = "allow"
or_fun_call = "allow"
multiple_crate_versions = "allow" # should this be on allow?
missing_errors_doc = "allow"
cognitive_complexity = "allow"
float_cmp = "allow" #TODO: this should be changed and f32/f64::EPSILON should be used
doc_markdown = "allow"
too_many_lines = "allow"

but there might be better ones we can use.

Also, we need to investigate how many issues this will result into, and how much effort it might take to do a cleanup of this.