extension/src/goTools.ts: remove unused fields from Tool.

`close` was used to shut down old tools like `gocode`.
That is no longer used. Delete it.

`maximumGoVersion` was used when the extension had to
choose different tools depending on the go version.
We no longer use it. Delete it.

Change-Id: Ie4963c084f78b5d3c853fcf6a2828af2aacb318f
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/618355
Commit-Queue: Hyang-Ah Hana Kim <hyangah@gmail.com>
kokoro-CI: kokoro <noreply+kokoro@google.com>
Reviewed-by: Hongxiang Jiang <hxjiang@golang.org>

extension/src/goInstallTools.ts

@@ -289,14 +289,6 @@ async function installToolWithGo(
 	goVersion: GoVersion, // go version to be used for installation.
 	envForTools: NodeJS.Dict<string>
 ): Promise<string | undefined> {
-	// Some tools may have to be closed before we reinstall them.
-	if (tool.close) {
-		const reason = await tool.close(envForTools);
-		if (reason) {
-			return reason;
-		}
-	}
-
 	const env = Object.assign({}, envForTools);
 
 	let version: semver.SemVer | string | undefined | null = tool.version;
@@ -365,14 +357,6 @@ export async function promptForMissingTool(toolName: string) {
 		);
 		return;
 	}
-	if (tool.maximumGoVersion && goVersion.gt(tool.maximumGoVersion.format())) {
-		vscode.window.showInformationMessage(
-			`You are using go${goVersion.format()}, but ${
-				tool.name
-			} only supports go${tool.maximumGoVersion.format()} and below.`
-		);
-		return;
-	}
 
 	const installOptions = ['Install'];
 	let missing = await getMissingTools();

extension/src/goTools.ts

@@ -37,15 +37,9 @@ export interface Tool {
 	latestPrereleaseVersion?: semver.SemVer | null;
 	latestPrereleaseVersionTimestamp?: moment.Moment;
 
-	// minimumGoVersion and maximumGoVersion set the range for the versions of
-	// Go with which this tool can be used.
+	// minimumGoVersion sets the minimum required version of Go
+	// for the tool.
 	minimumGoVersion?: semver.SemVer | null;
-	maximumGoVersion?: semver.SemVer | null;
-
-	// close performs any shutdown tasks that a tool must execute before a new
-	// version is installed. It returns a string containing an error message on
-	// failure.
-	close?: (env: NodeJS.Dict<string>) => Promise<string>;
 }
 
 /**