Updates to use rust 1.85. Doesn't move to the 2024 edition, as that's a
fair bit more involved.
A nice side benefit is that the new rustc version seems to lead to a
slight reduction in binary size (at least on mac):
```
FILE SIZE
--------------
+4.3% +102Ki __DATA_CONST,__const
[NEW] +69.3Ki __TEXT,__literals
[NEW] +68.5Ki Rebase Info
+5.0% +39.9Ki __TEXT,__unwind_info
+57% +8.85Ki [__TEXT]
[NEW] +8.59Ki Lazy Binding Info
[NEW] +5.16Ki __TEXT,__stub_helper
[NEW] +3.58Ki Export Info
[NEW] +3.42Ki __DATA,__la_symbol_ptr
-0.1% -726 [12 Others]
-21.4% -3.10Ki [__DATA_CONST]
-95.8% -3.39Ki __DATA_CONST,__got
-20.9% -3.43Ki [__DATA]
-0.5% -4.52Ki Code Signature
-100.0% -11.6Ki [__LINKEDIT]
-1.0% -43.5Ki Symbol Table
-1.6% -44.0Ki __TEXT,__gcc_except_tab
-0.2% -48.1Ki __TEXT,__const
-3.3% -78.6Ki __TEXT,__eh_frame
-0.7% -320Ki __TEXT,__text
-1.5% -334Ki String Table
-0.5% -586Ki TOTAL
```
Support HTTPS protocol for otel exporting. Includes support for
`OTEL_EXPORTER_OTLP_CERTIFICATE`, `OTEL_EXPORTER_OTLP_CLIENT_KEY`, and
`OTEL_EXPORTER_OTLP_CLIENT_CERTIFICATE`
Fixes: https://github.com/denoland/deno/issues/27703
split up otel config into user configurable and runtime configurable
parts. user configurable part is now set via env vars parsed according
to the otel spec. otel is now enabled via `OTEL_DENO=true`, and
`--unstable-otel` only acts as a guard.
Fixes: https://github.com/denoland/deno/issues/27273
