Allow APP_VERSION to be empty string + dockerFile fix (#10900)

# Introduction
No choice but to allow APP_VERSION to be an empty string as it's though
to dynamically define dockerfile env vars

packages/twenty-server/src/engine/core-modules/environment/decorators/is-optional-or-empty-string.decorator.ts

@@ -0,0 +1,7 @@
+import { ValidateIf, ValidationOptions, isDefined } from 'class-validator';
+
+export function IsOptionalOrEmptyString(validationOptions?: ValidationOptions) {
+  return ValidateIf((_obj, value) => {
+    return isDefined(value) && value !== '';
+  }, validationOptions);
+}

packages/twenty-server/src/engine/core-modules/environment/environment-variables.ts

@@ -28,6 +28,7 @@ import { CastToPositiveNumber } from 'src/engine/core-modules/environment/decora
 import { EnvironmentVariablesMetadata } from 'src/engine/core-modules/environment/decorators/environment-variables-metadata.decorator';
 import { IsAWSRegion } from 'src/engine/core-modules/environment/decorators/is-aws-region.decorator';
 import { IsDuration } from 'src/engine/core-modules/environment/decorators/is-duration.decorator';
+import { IsOptionalOrEmptyString } from 'src/engine/core-modules/environment/decorators/is-optional-or-empty-string.decorator';
 import { IsStrictlyLowerThan } from 'src/engine/core-modules/environment/decorators/is-strictly-lower-than.decorator';
 import { EnvironmentVariablesGroup } from 'src/engine/core-modules/environment/enums/environment-variables-group.enum';
 import { ExceptionHandlerDriver } from 'src/engine/core-modules/exception-handler/interfaces';
@@ -984,7 +985,7 @@ export class EnvironmentVariables {
     group: EnvironmentVariablesGroup.ServerConfig,
     description: 'Twenty server version',
   })
-  @IsOptional()
+  @IsOptionalOrEmptyString()
   @IsSemVer()
   APP_VERSION?: string;
 }