Allow specification of a custom interface name

[queengooborg]

This PR adds a new tsName schema property that allows a developer to overwrite the default generated name. This is super helpful in cases where two interfaces/types are generated with the same name (and one has a numerical increment), or where the developer may wish to ensure backwards compatibility of their TypeScript definitions.

Before:

/**
 * This interface was referenced by `Browsers`'s JSON-Schema
 * via the `definition` "browsers".
 */
export type Browsers1 = Record<string, BrowserStatement>;

export interface Browsers {
  browsers?: Browsers1;
}

After:

/**
 * This interface was referenced by `Browsers`'s JSON-Schema
 * via the `definition` "browsers".
 */
export type Browsers = Record<string, BrowserStatement>;

export interface BrowsersData {
  browsers?: Browsers;
}

This is related to #181 (and potentially resolves it?). Unlike #215, however, this PR aims to grant the developer more finite control over the names.