Add upper and lower helper methods for bundle templates (#3242)

## Why
Resolves #3237

Implements the feature requested in
#3237.

## Tests
Acceptance test

Author: shreyas-goenka

acceptance/bundle/templates-machinery/helper_upper_lower/databricks_template_schema.json

@@ -0,0 +1,9 @@
+{
+    "properties": {
+        "s": {
+            "type": "string",
+            "description": "An input string",
+            "default": "AbCd0123😀"
+        }
+    }
+}

…emplates-machinery/helpers/out.test.toml …chinery/helper_upper_lower/out.test.tomlacceptance/bundle/templates-machinery/helpers/out.test.toml renamed to acceptance/bundle/templates-machinery/helper_upper_lower/out.test.toml acceptance/bundle/templates-machinery/helpers/out.test.toml renamed to acceptance/bundle/templates-machinery/helper_upper_lower/out.test.toml

@@ -0,0 +1,7 @@
+
+>>> [CLI] bundle init .
+✨ Successfully initialized template
+
+>>> cat hello.txt
+abcd0123😀
+ABCD0123😀

acceptance/bundle/templates-machinery/helper_upper_lower/output.txt

@@ -0,0 +1,4 @@
+trace $CLI bundle init .
+
+trace cat hello.txt
+rm hello.txt

acceptance/bundle/templates-machinery/helper_upper_lower/script

@@ -0,0 +1,2 @@
+{{ .s | lower }}
+{{ .s | upper }}

acceptance/bundle/templates-machinery/helper_upper_lower/template/hello.txt.tmpl

@@ -0,0 +1,5 @@
+Local = true
+Cloud = false
+
+[EnvMatrix]
+  DATABRICKS_CLI_DEPLOYMENT = ["terraform", "direct-exp"]