Dashboards: Add join and customqueryparam template variable formatters (#107904)

* Update scenes lib

* update schema for customqueryparam formatter

* add docs for new formatters

* fix docs example

* sort alpha

docs/sources/dashboards/variables/variable-syntax/index.md

@@ -94,6 +94,16 @@ String to interpolate: '${servers:glob}'
 Interpolation result: '{test1,test2}'
 ```
 
+### Join
+
+Formats multi-valued variables with a custom delimiter. If no delimiter argument is supplied, they will be combined with `,`.
+
+```bash
+servers = ["test1", "test2"]
+String to interpolate: '${servers:join:&}'
+Interpolation result: "test1&test2"
+```
+
 ### JSON
 
 Formats variables with multiple values as a comma-separated string.
@@ -134,6 +144,24 @@ String to interpolate: '${servers:pipe}'
 Interpolation result: 'test1.|test2'
 ```
 
+### Query parameters
+
+Formats single- and multi-valued variables into their query parameter representation. Example: `var-foo=value1&var-foo=value2`
+
+```bash
+servers = ["test1", "test2"]
+String to interpolate: '${servers:queryparam}'
+Interpolation result: "var-servers=test1&var-servers=test2"
+```
+
+Use the `customqueryparam` formatter to customize how the query parameters are formatted. It accepts two optional arguments to specify the parameter name, and a value prefix.
+
+```bash
+servers = ["test1", "test2"]
+String to interpolate: '${servers:customqueryparam:v-servers:x-}'
+Interpolation result: "v-servers=x-test1&v-servers=x-test2"
+```
+
 ### Raw
 
 Doesn't apply any data source-specific formatting to the variable.
@@ -194,13 +222,3 @@ servers = ["test1", "test2"]
 String to interpolate: '${servers:text}'
 Interpolation result: "test1 + test2"
 ```
-
-### Query parameters
-
-Formats single- and multi-valued variables into their query parameter representation. Example: `var-foo=value1&var-foo=value2`
-
-```bash
-servers = ["test1", "test2"]
-String to interpolate: '${servers:queryparam}'
-Interpolation result: "var-servers=test1&var-servers=test2"
-```