properly convert env interactions into context

This input:

```yaml
{% set a = environ["a"] %}
{% set b = environ.get("b", "0") %}

package:
  name: abc
  version: 0
```

on `main` emits this recipe that needs manual correction:

```yaml
schema_version: 1

context:
  a: "\"env.get(\"a\")\""
  b: "\"environ | get(\"b\", \"0\")\""

package:
  name: abc
  version: 0
```

but after this PR, it will instead emit:
```yaml
schema_version: 1

context:
  a: ${{env.get("a")}}
  b: ${{env.get("b", default="0")}}

package:
  name: abc
  version: 0
```
which does not need any further editing.

conda_recipe_manager/parser/_types.py

@@ -132,6 +132,11 @@ class Regex:
     # Finds `environ[]` used by a some recipe files. Requires a whitespace character to prevent matches with
     # `os.environ[]`, which is very rare.
     PRE_PROCESS_ENVIRON: Final[re.Pattern[str]] = re.compile(r"\s+environ\[(\"|')(.*)(\"|')\]")
+
+    # Finds `environ.get` which is used in a closed source community of which the author of this comment
+    # participates in.
+    PRE_PROCESS_ENVIRON_GET: Final[re.Pattern[str]] = re.compile(r"\s+environ \| get\((\"|')(.*)(\"|'), *(\"|')(.*)(\"|')\)")
+
     # Finds commonly used variants of `{{ hash_type }}:` which is a substitution for the `sha256` field
     PRE_PROCESS_JINJA_HASH_TYPE_KEY: Final[re.Pattern[str]] = re.compile(
         r"'{0,1}\{\{ (hash_type|hash|hashtype) \}\}'{0,1}:"

conda_recipe_manager/parser/recipe_parser_convert.py

@@ -132,7 +132,7 @@ def _upgrade_jinja_to_context_obj(self) -> None:
                 self._msg_tbl.add_message(MessageCategory.WARNING, f"The variable `{name}` is an unsupported type.")
                 continue
             # Function calls need to preserve JINJA escaping or else they turn into unevaluated strings.
-            if isinstance(value, str) and search_any_regex(Regex.JINJA_FUNCTIONS_SET, value):
+            if isinstance(value, str) and (search_any_regex(Regex.JINJA_FUNCTIONS_SET, value) or value.startswith("env.get")):
                 value = "{{" + value + "}}"
             context_obj[name] = value
         # Ensure that we do not include an empty context object (which is forbidden by the schema).
@@ -738,6 +738,16 @@ def pre_process_recipe_text(content: str) -> str:
                     f"env.get({quote_char}{key}{quote_char})",
                 )
             )
+
+        for groups in cast(list[str], Regex.PRE_PROCESS_ENVIRON_GET.findall(content)):
+            key_quote_char, key, _, default_quote_char, default, _ = groups
+            replacements.append(
+                (
+                    f"environ | get({key_quote_char}{key}{key_quote_char}, {default_quote_char}{default}{default_quote_char})",
+                    f"env.get({key_quote_char}{key}{key_quote_char}, default={default_quote_char}{default}{default_quote_char})"
+                )
+            )
+
         for old, new in replacements:
             content = content.replace(old, new, 1)
 

conda_recipe_manager/parser/recipe_reader.py

@@ -704,7 +704,7 @@ def render(self) -> str:
         if self._schema_version == SchemaVersion.V0:
             for key, val in self._vars_tbl.items():
                 # Double quote strings
-                if isinstance(val, str):
+                if isinstance(val, str) and not val.startswith('env.get('):
                     val = f'"{val}"'
                 lines.append(f"{{% set {key} = {val} %}}")
             # Add spacing if variables have been set